Price increase for loyal customers only and slow speeds

I have an uncapped 10mb/s fibre package with Vox Telecom. My package is supposed to be R799 per month. In January 2018 it was increased to R834.95. There website still advertised it as R799 and when phoning in there sales department also quotes it as R799, but there accounts department says there existing customers are subject to an increase. The sales consultant first suggested I cancel my package and repurchase it to maintain the price of R799, but there may be some down time. I was then contacted by the sales manager who informed me that he would revert my package to the original price, but two months later I'm still being charged the inflated price. There website advertises it at R807 now, but I am still being charged more than that. Why do I need to go through all this trouble just to maintain there advertised price each year and avoid an increase. There is no indication of these inflated prices on there website, nor do there sales consultants know anything about it. So the longer you stay with Vox Telecom the more you end up paying in the long run unless you willing to constantly cancel and repurchase the same product to maintain there advertised price. There vox uncapped voice is also so poor you can barely make out what the other person is saying on the phone. There internet speed has also been running slower than usual and lags when streaming 360p videos. For a 10mb it is running like a 2mb line.