Issues with depositing cash into CEX

Hi all,
For context I’m from the UK
I’ve had issues depositing cash into an exchange.
I’ve been using kraken, but both of my bank accounts - Royal Bank of Scotland, and NatWest, have reverted my transfer of ~£2,000.
They told me in a text message that this would continue to occur, “Funds have not left your account and future payments may be restricted.”
I have used Revolut, but their fees are terrible, and there is a £1000 limit for transfers a day. So it takes ages to be able to send off all my cash into my cold wallet.
Does anyone have advice?
Thank you