Those three numbers, when they are asked for, are entered in a separate field, not the one you put your card number in. But I'm sure you would have noticed if there was a blank field needing filling
It seems like your bank require those numbers to authorize the transaction, and Shrapnel is not asking them, or else you missed the field ?
I know I bought my copy from Shrapnel not so long ago, with my Visa card, and had no problem...