Has anyone else received "OUTSTANDING DEBT" letters from ARVATO?

• internet phone calls
• cheap phone calls
• tax write offs

I have received threatening letters from ARVATO BERTELSMANN claiming that I owe them money!

When I tried to phone them, I was informed that the number no longer exists.

Is this a genuine firm or a spoof?

Have any of you received similar correspondence?

Has anyone else received "OUTSTANDING DEBT" letters from ARVATO?