You know Clew
It is never a good idea to pay for anything online, or anywhere else, with your debit card because, if something goes wrong, things become very difficult when trying to get your money back.
Banks are very reluctant to refund money, and so take the loss, when somethings go wrong, even if it can be shown that it's not your fault.
A friend of mine was going into hospital for a minor op, but before going in he decided to check his bank account. Instead of seeing a healthy balance, as expected, he saw that he was £750.00 overdrawn. He had to cancel his op and get onto his bank to find out what had happened and try to get his money back.
After a week or two, the bank decided to refund all his money back to him minus £50.00. You see, even though it was obvious his money was withdrawn by someone inside the bank, the bank still decided to withhold £50.00 from his refund because, they said, he must have done something wrong.
As soon as he could, he transferred his money (salary + savings) to another bank.
Plus, I'm sure you know that if you buy a big ticket item with your bank card, i.e. anything costing £100.00 and over, and the retailer goes bust then you've lost your money. However, a credit card user in the same situation will get their money back.