A sum of money was deposited into account by a bank (ie not a transfer from a person's account, but the bank itself). The person who recieved the money called said bank to try to find out where it had come from, check if someone had fraudulently taken out a loan in their name, etc. Said bank has no record of the person's name, address, DOB etc. No account in their name.
Bank's customer service told person to email their fraud team and explain situation. No response.
What should that person do next? Seems to be a mistake by the bank, rather than a fraud attempt, but the person has tried to rectify to no avail. It's an online bank, so no branches etc.