Restrictuons on personal bank account

I received my gratuity amount on 15 March 2024rom the Government Employees Pension Fund upon retirement from the Public Service, which is in excess of R1million. FNB immediately placed a restriction on that amount and my bank account and since then I can not access my money and account, practically "freezing" everything. The Pensionfund provided a proof of payment letter, but FNB remains unco operative and keeps coming up with unreasonable and previously unmentioned reasons why the proof of payment letter did not comply with their provisions. The latest reason was that the letter did not have the office stamp on their official letterhead. I feel that FNB is just dragging their feet and being unnecessarily difficult in not releasing the constraint and releasing my money. I need to invest my money asap as my health situations has taken a turn for the worstby lising all vision in one eye and the other eye will follow suit and my time to make other arrangements for my care is extremely short and a crisis since this was never expected in my long term planning. I absolutely need andd want my oney rhat FNB is keeping hostage *******ly. It is my money qnd my bank account and thwy do not have the right to keep me away from what I have worked for and earned independently from First National Bank