Santander UK asking for crypto exchange logs

Santander UK have been threatening to restrict my account unless i answer their questions

I've been thru this 3 times now in the last few months, each time being told it was a basic KYC check. At first it was tame, with questions like, what is this external (well known savings account) payment for (in my own name) and why did it send me money back (to pay bills)

Followed up shortly with; why did this company pay you on these dates (My Employer)
We now get to recently and they want to know exactly the amount i sent to coinbase 8 years ago, how much and what crypto i bought with it, also how much is that worth now.
Same question about Kraken..

then the WTF... Please send us all statements from your external savings account, Coinbase and Kraken.

When saying this is an overreach of the KYC regulations as all the companies involved are UK also KYC certified, and FCA regulated, i have been told no it isn't.

For the record I've just been DCA into BTC from my wages. There isn't any sudden influx of unexplained money.

So i now have a new bank account with someone else.