I did not join membership but your automatically charge $99 form my credit card. Should be cancel and back the money.

Call your credit card company and have them cancel the charge.

Fixya cannot assist you with this problem, as it has nothing to do with Amazon. You should contact Amazon customer assist on

https://www.amazon.com/gp/css/homepage.html/ref=hp_gt_ss_myac

by clicking on "Manage Prime membership". Also don't forget you can ask your credit card provider to reverse the charge as it was not authorised.
.

Probably about 30 days after you agreed to a free trial. If you did not cancel, it started automatically - and charged $99 to your credit card. Contact Amazon directly for help with this.

Amazon com Online Shopping for Electronics Apparel Computers Books DVDs...

If the charge on your statement has a telephone number, call it. If you can use a recorder do that. They will likely try high-pressure techniques and may even refuse to refund the charge but this step is necessary before you call your credit card issuer. They can stop the charge and refund your money. Afterward, file a complaint with your local BBB or on-line with the city of the scammer, if you know it. Do NOT do do nothing. That will result in more charges.
(This is from personal experience. I have been battling these weasels for years and have a phony magazine subscription I am working on now,)

Hi Galal!

To end your Amazon Prime membership:

1. Manage Prime Membership .
2. Do one of the following:
   • To cancel a paid Amazon Prime membership, click End membership. Note: Paid members who haven't placed an Amazon Prime eligible order are eligible for a full refund. You can't receive a refund if any of the household members have placed an Amazon Prime eligible order.
     
   • To cancel an Amazon Prime free trial, click Do not continue. Note: If you don't cancel your Amazon Prime free trial, you will be automatically upgraded to a paid membership plan at the end of the trial period. You can find this date listed on the left-hand side of the Manage Your Prime Membership page. You will still have access to your Prime benefits until this date.
     

I hope this helps! Good day!

Contact bank or credit card and tell them it is not a legitimate charge

You are on Fixya.com not Amazon.

If you have already called / contacted them (under HELP & SUPPORT) and have not been able to get them to resolve the problem ... or change your membership to FREE ... instead of GOLD or PREMIUM, consider (1) advising your credit card carrier (VISA, MC, etc.) that the charges are NOT authorized ... providing them with some documentation/proof that you have already cancelled the account, but they keep charging you.
then (2)... change/remove the info for your (automatic) charge account ... e.g. credit card #, etc. and / or tell customer support you wish to cancel your account