DSTV Price Lock

My mother has been a client of DSTV for years now , so she has retired from work and i have taken over the payment plan . So i decided to have the Explora A3 installed with extra view on price lock. The installation happened end of July so then end of July the payment went off as R603.00, end of August i get debited R869.00 . Ive been sending mails to their price lock email address and havent received any response as yet. The plan is based on a fixed price of R549.00 which i understand the R603.00 but moving from there to R869.00 is ridicules. I have 2 reference Numbers now and still havent gotten a call from them