You quit using Amazon, because you couldn’t figure out how to put in your CC information?
Amazon’s help is very fast and easy to use. They have a staffed help desk for questions.
FWIW, if you want to make a purchase on Amazon after your cached card expired, you can choose to enter a new card.
There is nothing on Amazon I want that I can't buy elsewhere. They were trying to get me to jump through hoops, so I left. If Amazon was exclusively selling something I really wanted, I suppose I'd figure it out. AFAIK, Amazon is not exclusively selling anything I really want.
Put another way:
Amazon's help may be "fast and easy", but it still wasn't as fast and easy as just going to Ebay.