Takes for ever to return deposit

Bad service received. Moved out of office told them Friday 28th of the month is final day and they need to do reading. They only arrive on Tuesday (Friday was weekend). Ask for final billing - we have to wait for the filling run on the 15th of next month. Now after a full month since we moved out we get told it will take 45 days to do our refund. Why can companies demand deposits but cannot refund the deposits in 14 days