Billing Query

i have been struggling with telkom for the past 4 months with regards to a billing dispute I've been calling them everyday for 4 months and all they have been saying is they are working on it my line has been suspended despite me paying it every month and they making me pay cancellation fee for there mistake of a laptop but sending me a invoice of installment fee with the same laptop that was cancelled by them every month. This is unprofessional and reflects bad on my credit record because the matter still remains unresolved.