SH3 GWX3 escorts too smart after 1943?

[bartpl]

Hello there my fellow Kaleuns!
As a devoted SH3 GWX3 player I have a question, since I hit really huge wall in mid-1943. Which really discourage me from playing anymore. And I am still hoping to at last get that XXI command!
I mean escaping escorts after convoy attack in mid-1943 and later gets harder and harder, and makes me think that the only good choice if one want to survive is... not to attack the convoy. I tried several times already, starting a new campaign after being sunk, and every time I end up at the bottom of the sea. The thing is most escorts are possible to evade using methods described in GWX manual. However there is always one or two destroyers which always know your position, and you cannot fool them anyway. No matter what you do, bottom the boat (it doesn't work in SH3, have anybody heard of any mod fixing this?) or go really deep, like 250-300 m (thermal layers also don't work here I suppose?) I mean OK, if two DDs follow you, one can track you and other attack. But if just one destroyer keep following and attacking you, alone, for 20, 30, 40 hours, keeping to do so even when it used up all of his depth charges... Is this really realistic behaviour? Or rather should it give up finally and get back to guard convoy, revealing U-boat position to HK group or allied air forces? I noticed for example, that when you stop your sub just in the middle of DD's circling pattern, it will circle around you endlessly, doing nothing but turning the same direction with constant speed (yesterday it was about 1 hour 15 minutes; when I bottomed the boat at about 120m depth - DD was still circling the same way; when 20 minutes later I stood up from the bottom, started engines again and left "the magic circle" I was instantly DCed). I suppose that in real life DD's skipper would at least change circling direction in order to regain sonar contact or get a proper position to drop depth charges. I mean real people don't act that way, they act with elasticity to changing conditions, they also sometimes make mistakes. "Veteran" DDs in GWX3 don't make mistakes - why? (Yesterday, trying to evade that very destroyer I used up all of my decoys strictly following the tips in GWX 3 manual - and he got fooled only once, for two DC attacks, then found me again in no time).
As I mentioned before, I had this kind of situations before and I ran desperate, trying to sink destroyer with an acoustic torpedo (I managed to do this, but in couple of minutes I got three more destroyers on me and I got sunk) or with a deck gun (this time I managed to survive surprisingly to myself). I mean I know Kriegsmarine lost the war but is it really fair? Historically accurate? If I can't escape, using external view, than I suppose
it's like every single U-boat which tried to attack an allied convoy after 1943 and later got sunk.
Any useful tips? Mods? Ideas?

Oh, and one more thing. Sometimes weather could change in literally 5 minutes from clear blue sky to fog and heavy precipitation. It's so annoying when you approach your target. You take estimations to it's range and speed, hide the periscope and when you raise it five minutes later you can see nothing... I have never seen this kind of weather change in real life... Can anyone tell me is there any mod helping with this?

Many thanks in advance for reading my lengthy post and replying