Over billing( debiting more than what was agreed on)

On the 18th september I took out a price lock package that is currently on promotion, i advised that i am on the compact parkage and has never had a problem until this new product. I was advised that they will within three days deliver their Explora 2 decoder and that an installer details will be provided to come, to date nothing has happened and has been over charged in two consecutive months over R1000 and everytime i call, i am being taken to pillar and post, i am being promised that the price log department will call and nothing is happening, i have now run out of options as even the call centre people dont want me to talk to a manager, they are constantly in meetings. I want them to come and take their decoder as they are not doing business in good faith.