I stay on top of my credit report yearly. It take some time but I improved my score steadily as things dropped off from disputing them or from age.
Your report will vary depending on which agency you get it from. Get a 3 in 1 report so you can make disputes at all the agencys at once. I got a free one here:

Notify them in writing and ask them to correct your credit report. If you have anything to prove you were living elsewhere, send them that info.

If they balk, tell them to put a notation on your account that you dispute this item.

The best way to go about it is disputing the account with the credit reporting bureau and letting them take care of it.

You can not really do anything to expedite since the credit reporting bureaus are backed up with more pressing issues.

Also, call the creditor direct. The bank or entity wherein the loan originated and notify them. That will do it right away.

Look up the address to write them for disputing items on your credit report. Show them some documentation of your living arrangement at the time. Perhaps some tax record sent to an address, a utility bill in your name, something like that.

However, a person can have a mortgage on a property they don’t live in. Are you sure you didn’t co sign for anyone? If you didn’t, it’s ID theft and the first thing you should do is report it as a crime.