Has anyone ever had their bank account frozen after selling bitcoin? How was the process of getting it resolved? How long did it take? Any advice that I can speed the process up?

OK so sold around 5k worth via local bitcoins, various buyers. Few days ago my bank was frozen. Got zero help or answers or even questions from the bank. So I've done some googling and come to the conclusion that a SAR has been submitted due to sudden increase in money. Never really used this account and did so to separate it from salary for when tax season comes around in easy for me to know what is what. (probably not wise in hindsight)

So from my googling what the bank is calling "account specialist" is actually the nca deciding if I'm dodgy Dave or not and whether to investigate further. Nothing to hide so no worries there. Initially frustrated I requested my official complaint raised and have since had a response (again no info or help) but armed with the new information about SAR and the fact that legally cannot tell me anything I've replied with screenshots of my transactions of sales in hope it assists and speeds things along as they will then know where and why.

Is there anything else I can do to speed this up? I've read the hold is initially 7 days, followed by 30 and can be extended to 6 months. Obviously the bank cannot ask me for evidence(or anything else) due to the law but is there anything voluntary I can do? Really is a crazy system that you are kept in the dark.. While they also seem to investigate in the dark