Linebarger Goggan Blair Sampson LLC review: the company sent letter to my address, but the name on the envelope wasn't mine

I had the problems with Linebarger Goggan Blair Sampson LLC. I got the letter from them and it wasn’t for my name. I knew this name, because this person stole my identity couple of months before. It was my address on the envelope and I was confused. I informed the company about the previous situation, but no one responded. Please, help me or give any advice what to do next.