Sanlam service

I have a retirement annuity with Sanlam. The plan was to increase the monthly payment so I could put away a bit more. The following month after the discussion I had with my advisor the incorrect amount went off my account. More than the agreed amount obviously. It has been a 3 month struggle to get the situation sorted out after I have sent them the correct documentation. Every time I phone them, they are still busy investigating and my money can't be refunded. It is funny how quick the debit order can go off, but when it comes to giving your money back due to their incompetence, it can't be done. Extremely ticked off.