If you read about what to do after repossession you will see what the advice is on how to handle companies chasing for payments after repossession.(posted 8454 days ago)However, the very first thing you should do is get a SARN on the Bank/BS your mortgage was with.
As to the incorrect address, you don't say HOW wrong it is. Is it a case of there being a slight error and you can see it's MEANT to be your house, or is it clearly way off ? If the former then it's quite clearly documented what to do on this site. If the latter I'd suggest you write to them and simply state that you have NEVER lived at the address they give and that, consequently, you can only assume the letters have been sent to you in error.
No matter what you do - get the SARN first !!