Glad I'm not the only one in this awkward position - I have a balance due a couple of days ago and they have emailed saying they can only pay in two week's time on pay day! This is for Easter - I've t hought about it and I'm going to keep to my T&C's and tell them the cottage will be relisted and they risk losing the booking. I feel a bit harsh doing this but would Thomas Cook or another holiday company be soft? No.
This has only ever happened once before when I gave a week's grace which ended up being two weeks before the balance came in. In hindsight, after turned out to be the worst guests ever, I should have known they were trouble cancelled it there and then.
Don't feel harsh waterwitch. It's one thing to agree to a different timescale as I just have with a particular booking but guests can't inflict their cashflow difficulties on you. Can they pay by card? That way they are delaying payment two weeks at their end anyway.