I love the convenience of online shopping and use Amazon very frequently. I have had Prime for many, many years and have never had any of the problems you are complaining about. When I need to return something, the refund is prompt, often immediately after I have returned it at the UPS store. If I need to call for something, I find their customer support is excellent and fair. I recently ordered a mattress... one of the ones that comes rolled up in a very large box. It showed as delivered by UPS but it was not at my home. They replaced it immediately.

They promised me a refund for a $249.99 camera, and a fraction of the cost of the wasted instant film, many, many times last summer. They strung me along for months. I was very nice, and patient. Maybe it's because I'm female. Then they said, "This case is closed." I never had a problem with a product in the previous 14 years, and I never returned anything I bought to Amazon. But I have found errors, and they take sales tax sometimes for things that do NOT have sales tax, and I have gotten emails that refunds are coming (including service plan cancelations) and I have NEVER got ONE refund they ever promised, even after chatting or calling again. I spent a whole afternoon when I saw that $17 error, because they "chat" and leave the chat window and someone else starts over with you. They have to start over with you. They promised that $17 refund but once again, it never happens. I have caught errors in the past, and called and/or chatted, and was promised a refund, but I am NOT a vindictive person, and they have learned that people just forget about it.

I have had Amazon Prime for many, many years. They promised me a $17 credit into my account, before Thanksgiving. Once again, over and over again, I NEVER get the credit. They are making a fortune lying about credits. Returned items, over-charges, charging sales tax on things that do NOT have sales tax in Massachusetts. I have done the chats, phone calls, and they make promises, promises, lies, lies. They NEVER give you the credit. I've been ordering things several times a week for years. But I think this $17 is the final straw. I bought a camera that uses Fuji instant film for $249, and it was JUNK, (it just wasted expensive film = white) and I was promised a credit last summer. They are Lying about giving credits. They promised, but it was a LIE. If you contact them again, chat or phone call, they promise again, but it NEVER happens. Don't ever buy the service contract, if you cancel the order, you will NEVER get the refund for the service contract. OK, so it was only $3-$5 but it adds up.
So, today, I picked out some "deals" for Christmas. The sales price is NOT in the cart, the FULL price was there. The "Last Minute Deal" is a lie. You have 15 minutes to check-out, and I tried to check-out immediately. NONE of the prices in my cart were the sales price. I deleted everything in my cart but some vitamins. The actual vitamins I wanted are much much cheaper at CVS.
PRIME 2-day shipping guaranteed is a lie as well. Their prices are going up and up.