In certain circumstances The Financial Ombudsman service can be contacted to help with a dispute if a bank refuses to refund monies lost through a scam where a victim has transferred money to a fraudster. 

If victims are to recover their losses from any kind of scam it pays to exhaust all possible avenues. If money has been lost to a scam where their bank or The Financial Ombudsman service cannot help (such as through an investment scam) other options may be available and acting quickly can pay dividends. Speaking to a lawyer or recovery professional can be one of those avenues.

https://www.grantthornton.co.uk/investmentscams/