They're such sneaky little shits. A few years back I rang them and got my late-payment charges reversed on account of them moving my payment date forward to catch me off-guard.
At the same time I pointed out that I couldn't be paying the bills until I was paid so they'd have to charge me in the first week of the month for last month's bill.
This month they've tried it on again and made the payment date this Monday, meaning I had to pay March's bill by 8th April and April's bill by 28th April - not right and not good.
Looks like I'll have to ring them after the fact to get the charge repaid as it's too late now.
The moral of the story: always check your credit card companies aren't trying to fuck you over like this.