'Please help us to keep your account safe' - Locked out of account

I upgraded to Premium a couple of days ago as I exceeded my annual top-up limit. I then uploaded bank statements which took three days to verify.

Today I logged into my Revolut account and gave the four digits that appeared in my bank statement. Since then I cannot access my account and there is no explanation - only the message ‘Please help us to keep your account safe.’ Has anybody else had this problem and how do I solve this? I use my Revolut card daily so any advice/contact from customer support would be greatly appreciated.