If you have proof that you requested account closure and the fees continued, file a formal complaint and attach a copy of your closure request, its date, and any messages or statements that prove the fees were incurred after the request.
Do not automatically pay the fees without knowing why the account remained open, and obtain a complaint reference number.
The Central Bank published a similar case that ended with the fees being waived and the account being closed because the customer retained proof of their closure request.
The figures, fees and limits in this answer vary by bank and change over time — confirm them with your bank or the official source before acting.