OK, don't need ADM 137/3997 though it would contain additional details. Here's a summary of the action from "Reported Destruction of Submarines" (ADM 239/26):

July 25, 47°52’N, 11°44’W (Atlantic) Possibly slightly damaged

S.S. Baynyassa at 0600 sighted the periscope of a S/m on port bow. Headed for S/m in order to ram and succeeded in hitting her with port bow. S/m came to surface 10 minutes later. Ship opened fire and S/m replied with two guns. Fourth shot appeared to hit S/m. Smoke boxes were burning and when smoke cleared away the S/m was seen with her forepart under water.

Best wishes,
Michael