I've had this problem recently. My direct debit was cancelled by Plusnet before they processed a replacement. Despite the payment date you mention not occurring until after they say their system should have sorted things out.
From their website :-
"When you're ready to make the payment, all you need to do is log in to our website and you'll be taken directly to a page showing you how much is owed and when it was originally due. You can then choose to try again with your normal payment method,
or add a new card for one payment only (we'll only save this if you ask us to)."
This doesn't seem to work, unless I am missing something? I've asked them to take payment, but they don't seem able to.
I've added card details, but my bill is still showing as "Pending", despite the verified by Visa process having been completed OK.
Again their website says :-
"You have card details stored for your account. This isn't your primary payment method, however:
You can use your card to make quick one-off payments in the future
If we can't take your normal Direct Debit we'll use these details for payment"
When do they do that, as it's been 14 days since I asked them to change the account they take payment from?
When I ask a question it is answered by a reply of "question returned to customer".
I understand systems have bugs, but why not admit it and try and sort something out rather than wind customers up?
If the system had given me the chance to pay in advance (as you suggest) before it deleted my details I would have done, to save all this aggro!
Keef- Dartford Kent UK - Plusnet via Siemens Gigaset SE587
Previously - Virgin/NTL/Bell Cable, Crosswinds, IC24, FreeOnlineNet, X-Stream,
Totalise, Freeserve, Force9, TescoNet, AOL, Freenetname, Pipex, E7