I have an old contract, but since a few month it i...

I have an old contract, but since a few month it is impossible to reach anyone. I receive a regular letter with a lot of information on it and an address in Poland, but the phone number doesn't work and if you send a letter it will be returned ( undeliverable). That is spooky and doesn't make me feel good. I invested a lot money in a "life & pension" contract. I am living in Germany and nobody can assist here.