[mothered]

im about to start doing amazon refunds doing visa/mastercard egifts.
Im thinking about saying the code doesn't work for every one in three or four.

They'll most likely check Its validity on their end, hence deem the code Is working.

If this Is the case, you need to be adamant that It's not working on your end. If you're planning to SE them multiple times, they will realize what's going on.