Misled by company to pay price lock

I've been a loyal customer for years now but they have proven themselves wrong. I recently changed to DStv explora and I had an extra view already installed, I was assured that with the price lock only R499 for two years will be deducted nothing more, but last month an amount of R1671.00 was deducted . I tried contacting them to find out why using my own airtime but I was put on hold for long, eventually after calling again they told me that they are still looking into it , they will call me back immediately ,that was 2 days ago. This for me is unacceptable , they mislead viewers with this pricelock thing and they don't stick to the end of their deal at the end.