Double debiting on investment policy

I have 6 policies with old mutual , one of them is an investment of R500 but from July it' has been debited twice with the same policy number. I tried calling the customer care line and even sent through my pay slip clearly illustrating the two deductions of R590 but to my surprise old mutual is saying it can only see one amount. I have no choice but to refer this matter to my lawyers and also take my money somewhere else. I call this ***** and I never expected this from a trusted brand like old mutual. I pay more than R2000 a month on all my policies and never expected this kind of service from them. I want my money back.