ok firstly you dont need to get a mod to buy to proove your legit...
just simply get the cards together or 1 in this case and put your name on some paper and a date or put them buy your laptop/pc screen on your user profile logged in and take a picture and upload but you must take one of the back to proove the code has not been scratched off! ... there then is enough proof for people to stop calling you a scammer.. thefore its an easy life...