Unless I've misread, you say your cousin sent money to your bank but I don't get it, if your cousin sent money to your bank and then you deposited with your own card, how can they possibly know your cousin gave you the money unless you tell them or they asked you to do a source of wealth check and saw it themselves. If none of these outcomes are the case, then from what they say "using a third party payment method" sounds like you've actually used their card to deposit, which is a big no no for any legit site I'm sure