Salary payments

I worked for First National Bank for about 3 years. With in that 3 years there where months where I would receive my salary late or the following month for the previous month. On the month of which my contract ends, they simply decided not to pay me at all. When I logged my complain they insisted that I was paid but proof n records reflect that no payment was made. Till this very day I'm still waiting for my salary even their head of payroll can't seem to find the problem, on top of that they froze my account.