Outsurance = reverse Robin Hood

My partner took out an car insurance policy at outsurance. We never noticed but from day one a claim of R80000 was tagged to his name. This obviously affected his monthly premium amount. Only recently I noticed this and confronted outsurance regarding, they accepted the fact that is was their mistake and subsequently dropped the premium by more than R150 per month. Fine, thank you, NOW, the issue is that we paid a incorrect premium for more than two years? We want all the money paid incorrectly back! We were told ((telephonicaly) ->(i asked for documentation but was denied)) that the actuary dept is handling this and will refund us R400. R400!!? you dropped the premium by R150 per month, thereby admitting that this is the amount or closely to it, we were over billed! Can i donate a calculator to you guys because the way i work it out its definitely not R400! This whole matter was taken on with outsurance who said they will phone me back. I am still waiting. Not cool since I was was the one that recommended them.