I am no banker, but I do use 2 types of direct transfer in the UK, and I know this is a popular way of paying in Europe.
Both require you giving your customer an Acc Number, account name, sort code and bank name, they then phone their bank with these details, and the amount, and the money is transfered.
If you want this done immediately, then you have to pay (£25 in the UK), unless you are both in the same bank.
If you are prepared to wait three days, then there is no charge.
Easy. From the merchant point of view it is great, as there are none of the security problems associated with Credit cards.
Problems? Can they remove money from your account, knowing the details? No. They need more info. (Password etc) As a precaution it is worth setting up an account with Zero overdraft, and a weekly sweep into your usual account. That has got to be fool proof.
Hope this helps,