As i said amazon will can cancel any type of credit code and any time they want as they found abusive in there service(like for example same ip registration on mulitple accounts and other abusive type.I can't help you out regarding with that.As i sell valid codes only and test out on my personal account before selling this out.Hope everyone understands and read the Amazon Web Service Terms and Condition.
Regards.
I can't say I am satisfied with the outcome as I only have 1 account, 1 credit applied, credit card and number attached so there isn't any abuse on that front but thanks for the reply and your take on the situation.
Edit: I am retracting/correcting my statement (quoted below) as they were worded badly. Thank you for your reply on the situation crypto-bit