Should I jump through hoops to be paid for a job completed

[orangesnapples]

Hi.
I don't know if I'm being unreasonable.
I'm self employed and was booked by a local establishment.
Invoice was sent a week before the job,
Work was completed and received fantastic feedback.
After week or so AFTER the job I inquired about the clearing of the invoice and was told I would have to complete their in house system.
Which took me several hours and 2 calls to the help line just to get on to the system.
Was told it would be 6 days from then. That was the first week of August and I still haven't received pay.
I have messaged the client who booked me twice since asking for the invoice to be cleared.
Today I asked that the balance be cleared by end of the day.
I received a reply that I need to redo their system AGAIN.
I have refused and explained that my fee has not taken into account all of this extra admin work as I was not aware of this system until after the job had been completed.
I have been in this business for 12 years and have never had to go through this process, and iv worked for some pretty big corporations.
This is a local establishment.
Am I being unreasonable in refusing to start this process again.

Yes I have actually been back on the website done all the things and then told them they have 7 days to clear the invoice.
They keep sending messages saying the same that if I'm not paid it's because iv done something wrong. So instead of going back and forward. I'm just resending my last message. That I was not informed of this long process and that my quote would have reflected this if I had and I look forward to receiving the outstanding balance.

Has it been over 30 days yet? If so, reinvoice including a late payment fee. There is legislation that supports doing this. They'll suddenly pay up then.

And yes keep chasing. If we don't that's how these dodgy business get away with it.

Do I understand correctly that you've worked on their website?

Undo the work you've done if they don't pay you.

That'll get their attention.

It’s literally what I do. And I get paid via my payment terms. Happy to set up with a company if it’s going to be repeated work but I’ve never had this issue with non-payment, errors on their system or refusal to pay by the method indicated on my invoice.

I make payments be paid upfront because oc having to chase people so much, it is really depressing how many people won't pay invoices.

Making a small claim - Citizens Advice this has a template too