Wrong instalments

I was paying R299 for Vodacom home data sim card and I called to enquire about my phone contract and I was sold a router of R30 per month till end of the contract to my surprise in the month the amount increased from R299 to R833 , I called in to enquire and I was told I upgraded and the agent who sold me router made it clear that only R30 will be added to my contract ,I made follow up question regarding R30 only to be added and he confirmed ,now am told am gonna pay R833 every month ,I request to cancel data deal and I was told I will be called today and am still waiting for the call….I am so disappointed