No response from "Price lock deprtment"

My wife took out a contract with multi choice on a price lock bases and the package included an Explora decoder, Wi-Fi connector and installation for R499 including monthly subscription. However, the billing that we have been receiving since we started using this decoder is more than the R499 that was agreed and we have been querying this with the customer service department and we were informed that the Price lock department will call us in 24 hours as the matter was escalated to them. This was last month. On the 15th of this month we were informed that we owe R1099 and if we don’t pay, our subscription will be suspended, of which this was done few days later. We then contacted the same customer service department to query the amount once more and we requested that we go through the entire billing and analyse what could be the cause of this excessive billing, given that we should be paying R499 and not anything more. The customer service representative took us through oour billing and she noted that we have been paying more than the agreed amount of R499 and we have been billed more than the agreed amount. However, she couldn’t help us since the matter is not for their department as customer services but that of “price lock department”. We were once again promised that the price lock department was to contact us within 24 hours as the matter was escalated to them. Unfortunately, the 24 hours has passed and we have not been contacted by price lock department. And what’s frustrating is the fact that there’s no number where we can contact these so we can get clarity. We are not satisfied with kind of service at all.