Hens still havent paid me back?

Exactly. Why do people always suggest things like this? Be direct and upfront.

Why say the thing about the credit card?

There's no need to make up an excuse/ lie, that's just weird.

OP you just say bluntly that you're £400 out of pocket and they need to pay by X date or the trip is cancelled/ bride is paying for herself.

Name those who haven't paid and post a daily update of the list of names.

Same!!

Hi ladies, I'm still £400 out of pocket as no one has yet paid their £20 for brides portion. Please can everyone pay by the end of this week, I can't afford to carry this amount.

I’d send a breezy message to say “hi, I’ve got to pay off my credit card by the end of the week so need everyone’s £20 to do this - please send over before Friday…. Include details. Thanks all.”

If you want to be diplomatic:

Dear Hens,
Six months ago we made plans for "Brides" hen do. You all agreed to pay £20 to cover her costs. I agreed to pay up front and you all agreed to pay me back. Despite several requests most of you still owe me the money. I'm sure you would feel that was unfair if the tables were turned. In case you still don't have them, here are my bank details:
I'm afraid if everyone doesn't pay by Friday I will have to cancel the whole hen do and inform "Bride" why as I cannot afford to subsidise your share any longer.
Thanks, Purple

They agreed to cover the bride's share. If anyone objected they needed to say so 6 months ago.

You need to say that everyone who hasnt paid the £20 each needs to do so within the next 7 days or you will need to tell the bride that some people changed their minds and she will need to pay after all for whatever hasn't been covered.

I suggest wording it like that because it suggests some have paid and some haven't (and it's true - YOU have paid). It might help make people feel embarrassed that they might be the only one or two that haven't paid up and that the bride might ask who they are!

I hope you get it sorted. Never a good deed goes unpunished ...

It’s bad they haven’t returned the money. I’d name and shame them in the group chat and put some sort of message in about how it will be cancelled/ others will have to pay if they don’t cough up!
Even if they felt obligated, tough! They are adults and can say no before leaving someone else out of pocket!

I completely thought this was going to be about your chickens not laying yet!

I'd write in the group WhatsApp something like:

You all owe me £50 for Bride's trip. If you've decided not to pay, no worries, I'll ask Bride for it instead.
Monzo details xxx, paid in the next 24 hours please, thanks!

Put a Poll “Paid £20 for bride yes/no” In the group WhatsApp for the hen party, Pin it so it’s at the top.

Put your bank details or PayPal in a WhatsApp message and pin that t the group too

Send a reminder “hey ladies I have credit cards to pay so please cough up your share by end of day Saturday thank youuuuu”

then after saturday send a daily list of “not paid” names

That's irrelevant now as it was already agreed and done. The OP is £400 out of pocket and people need to cough up their share.

Sent everyone a Paypal request with their share.

Just say they have until ** date to pay and then you’ll be asking the bride to pay for herself.

Personally I think it’s cheeky to ask to cover the bride’s cost even if others have done this previously. Life’s getting more and more expensive, fair enough if people are feeling the pinch.

This 100%

Another vote for posting to say you are going to ask the bride to pay for herself, I wouldn't piss about with individual messages or chasing any longer.

I was about the say exactly the same thing. You are far more likely to get a response if you message them individually. In a group setting they can see that no one else has replied so it’s easy to blend in. If you message them one-to-one they can’t avoid you as easily plus it might give them the impression they’re the only one left that hasn’t paid.

Me three!!

Make it absolutely clear that you are £400 out of pocket because of their behaviour. Each of them will be thinking individually 'oh its just 20 quid, I can pay her when i see her'. They need to be shown the bigger picture - you are £400 out of pocket.

Infuriating. You need a strong message now:'I paid for the brides share 6 months ago and noone has paid me back. I need the money so please let me have it by Friday.' Then another reminder on Saturday if necessary.

Me too, I was just going to say to give it more time, they will lay eggs eventually.

“Hi Everyone, thank you to those who’ve paid up so far. Can I ask those who haven’t yet paid to pay £ [amount] into my account [detail] by Friday latest. This is the amount everyone agreed to contribute to cover [brides] share and I paid it upfront 6 months ago, so would like to settle up. I have sent a few reminders, but if I haven’t received payments by Friday then there we may need to let [bride] know [that her hen has to be cancelled as her share hasn’t been covered] [that some people didn’t pay up and that she’ll have to pay the difference].”

the implied naming and shaming should encourage those who haven’t paid to cough up

Check the cancellation policy! And cancel it if you can.

You just need to be really blunt now.

£20 each is hardly significant for each of them. I don't understand why they have not yet paid. Get at least one person to pay you, and then name that person as having paid and the rest as not having paid. Be very specific. Each one is hoping you think they have paid (or think they have paid, but haven't). Without pointing fingers, nothing will happen.