Additional calls charges above agreed calls limits.

I upgrade my cell phone contract at Nelspruit Riverside Mall last March and I signed limit of R1 and for the past 9 months I was charged additional amount above the R1 limit that is in my contract. And when I call customer services my call is being rerouted to collection department because of arrears amount resulted to additional calls chargers. People at collection department they said there's nothing they can do and my call cannot be transfer to customer services. My concern is to get the copy of my contract to see why the R1 limit was not implemented.