Question about SC mission for Dangerous Waters + RA

[FlyingTiger]

Hi folks,
So I am new to this whole game and I did read manuals and other guides to know my way around the sub. I am playing on severomorsk mission (dropping SEAL), with the FF pinging constantly and having to reach the destination at 2200 hours, I have to do at least 7 knots in the 688i. Upon reaching russian water, eventually, I got torpedoed, supposedly by surface ships. So, I deployed passive CM, because I think that torps from surface ships will be doing passive search first, then accelerated to around 10 knots, going sideway to escape torp's search cone. Then along the way, there were more TIW warnings (with my heading at 240, the torps bearings were on my aft, roughly 325- 340) so I dumped more CMs and accelerated to full speed. But in the end I got destroyed. Could anyone please tell me how do I deal with this situation? Thank you.