Why is "pay after delivery" not always available?

[Bavmorda]

Does anyone know the answer to the above? The only time it seems to be available is just after payday (when I don't need it and would rather the money went out immediately). When payday is coming up and I would like to use it, it's never an option. I've set it as my preferred way to pay.

I did contact them to ask and they didn't respond.

Thanks

It isn't available on all purchases.

Maybe the sellers you are using don't offer that option I was asked if I wanted to have the facility and I refused the option,I want to be paid straight away,you can't go into M&S and ask them can you pay next payday can you ?