Interesting and exciting patrol you had going there. It's a real pity about the CTD but I suppose you could say that a "higher power" saved you from a worse fate at the hands of those escorts.
Destiny is a malleable thing in the Twilight Zone.
(Now that reminds me of that really cool TZ episode where the u-boat captain is forced to live the same night over and over as a passenger aboard the liner he sank.)
I generally do my utmost to avoid setting still, trying to "wait it out" and hope the escorts lose interest. I use every evasive move I can to throw the escort off and get into his baffles, open the gap more, and then turn away from his path to put as much distance as possible between us and widen the circle. As the escort begins turning and I come out of his baffles, I'll order an "all stop" and then coast on the momentum I have from dashing away at flank speed. I'll give the order to resume silent engine speed once I've drifted back down to 1kt, but I won't make 2kts until there's at least 3,000 meters between me and the escorts. Once you reach 6-7km distance, you can usually just surface the boat and run like hell! Bad weather that reduces visibility will also work to your advantage by allowing you to surface sooner and thereby getting out of the ASDIC detection cone. Keeping your depth around 7 meters while surfaced will leave just your conning tower above water and still allow you to run the diesels, but don't do that in rough seas. This is called running with "decks awash" and has the two main advantages of making your already small silhouette even smaller and thus harder to spot from the enemy's decks as well as reducing your dive time dramatically which is extremely useful for avoiding enemy aircraft and avoiding crash dives in shallower waters which always seemed to end up with my bow getting dented before I could pull out and level off my depth.
Good luck nailing the Nelson on your redux of patrol 5, Abd_von_Mumit!
My patrol for Operation Wesserubung off the coast of Norway at grid AF59 was very boring. I suppose the foul weather kept the Nelson's task force away. I actually saw a German naval artillery barge go down because of the rough seas.