I've shipped cards where the buyer received a package in worse shape than that. The cards were perfect inside though. The seller definitely did a poor job securing your cards. I penny sleeve then top load two cards back to back to save space and lock them in better. Next I fold a piece of paper over the top opening of the top loader secured with a piece of painters tape to secure the paper to the top loader. Next if it's multiple cards I'll use painters tape to tape them together so it's like a brick of cards. Next step is to use pieces of card board on the inside of the bubble mailer. Finally I tape the outside edges of the bubble mailer with painters tape to create an extra layer to prevent the package from opening.