DSTV Billing continues to overcharge clients

I have signed up with DSTV for a 2 year contract on discounted rate of R850pm, they have been charging me different rates since the start of this i spoke to a lady last month who apparently confirmed my contract should be R850pm and she has now resolved the matter. Today I receive a bill for R939pm for the same service. in addition to the billing issues DSTV then has continuous error when you try to stream even from one user.