TELKOM *****

I took out a Telkom contract through Mondo in November. The installment of the 2 devices that I agreed upon is R502 a month but now Telkom is telling me that it's R550. Tried calling all the telkom customer care numbers as supp**** by the telkom consultants but still no one can sort this problem out for me. Now I'm stuck with paying an amou t that I never agreed upon.