Hi Mozalina,
I will also have to implement something like this: an additional fee for a certain payment method. I'll let you know, when I've managed it. (But sorry: It won't be tomorrow
)
But I believe, that you won't be able to accomplish what you want by edititing templates. Probably one has to change a few php scripts and - for a clean solution even some small changes to the database should be required (additional field in table xcart_payment_methods)
However, I also want to mention, that I believe, that it would make great sense, if this functionality would be incorporated in future releases of xcart, since for example here in Germany it is absolutely common to charge extra for the payment method COD (Cash on delivery)
regards,
Chris