Puzzle about grandfather

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Hi all, it has been a long time since I have posted here. I have scoured for more information on my grandfather and have hit a puzzle. According to a tape he made back in 1985, he was at Stalingrad at Christmas 1942. He said that his unit found out they were surrounded that day and "had to fight their way out. Which is what we did." The next thing he talked about, he was in a hospital in Czechoslovakia. There has never been an explanation as to how he got out. I wrote to WaST years ago and never sent in the Euros to get the full record (yes I kick myself almost daily). Anyway, someone got my sister to a list of Knight's Cross recipients and there was a Heinz Schacht awarded a Knight's Cross on January 19th, 1943. My mother says she never saw a medal, but there could be multiple reasons for that. The website says he was with 2./Panzer-Jagd-Abteilung 158. Near as I can tell, that unit was attached to the 58th infantry division in 1944 (no record for prior). The 58th Infantry Division was not at Stalingrad.