Sneaky interest?

tambu2too

I have a credit card with RBS and recently used their online credit card Facility to change my payment date to the beginning of the month from the middle of the month. This month my online account says that the payment is due on 3rd April but my paper statement says the payment will be collected on 23rd of March. I thought this was an error so called them and they advised that they debit the money from my bank account a whole week before it is due.

3
points:

1. Is this standard practice or specific to Rbs?
2. Is everyone else aware of this?
3. Is it right that a quarter of the time RBS are making interest off my money.

Even if this is the case, I feel its a bad setup that their website allows you to request a new due date but nowhere does it tell you the date you select is actually a whole week after the date the money will leave your bank account!

Thoughts please?