someone just called telling me my account has been hacked. He wants me to go to www.fastsupport.com then he gave me a key code to put in. Do i follow his instructions.

Absolutely not!

A. Fastsupport does not provide Apple support at all, and

B. While the FastSupport GoToAssist is a legitimate product used by many company and contract IT support systems, it unfortunately is also very commonly used by scammers to get you to grant them remote admin access to your computer.

Never, ever follow any link or enter any data in any email or txt from anyone claiming they need or want you to log in somewhere, or provide confidential information. And I do mean never do that, regardless of where the messages seems to come from.

You can always contact Apple support yourself if you wish to check something, or simply check your own accounts yourself (https://appleid.apple.com/).

Apple will never call you unless you called them and asked for a call back. That is a scam/phishing call.