[REQ] Change/upgrade subs once docked

[thyro]

A couple missions back I've been offered a new sub, to replace my killer S-18. I've declined that replacemend in hope of getting new kit for S-18 (such as new tower with AA etc).

Anyway neither the game now gives me new kit to upgrade the S-18 either I'm able to change the sub for better one.

Is there a mod-guru that could point me at right direction or create a mod to deal with this bugged limited game and allow upgrades and sub upgrades once docked? I'm not asking to release all the subs/upgrades but at least release the offered sub and upgrades relevant to the date.