Excuses to avoid refunding savings

I requested a savings refund on the 25th January and until now I still haven't received it. On application I provided the proof of banking details and was subsequently asked for a stamped bank statement, which I also provided. Now I am told that the 3 month delay is due to them trying to verify the banking details with the bank. What was the point of the proof of banking details and the stamped bank statement? Does it take more than 3 months to confirm banking details with the bank? Please refund the money, it's not even a lot.