It doesnt matter what method of payment you made before.
But, now and in the future it is changing to Bank Transfer.
As wmcforum pointed out, its in the agreement when you join the scheme.
As Micky discovered, it is a difficult process if you try to do it your own way. I did not expect it to be so bad, but Micky pointed out the pitfalls.
I paid by Bank Transfer a week before collection, it was easy peasy. I just checked the car over on collection day before entering the PIN. No problems.
If they ask you to pay the AP a few days before collection day, just do it
It will be you that suffers the pain of debit and credit card nonsense. The dealership doesnt care if you shoot yourself in the foot. They gave leverage, you have none.