Multichoice(DSTV) Over Changing On Price Lock Package

I'm on price lock premium package, I'm used to paying R1108.00 per month for two exploras and insurances for them since last year November 2018, but multichoice has been charging me extra from last month I was changed R1276.64, I called them several times and I was told someone will call me back between 24 and 48 hours, but no one has called since today(19/10/2019) and now got a sms that says your next installment is R1147.97. They are still changing me extra and no one coming back with answers. I need to know what PRICE LOCK mean