Billed More than the Contract I agreed to

I entered in a contract back in July for their 40Gb (20 day and 20 night) special for R199.I am charged R462 every month with no explanation.I have called them numerous times to also pull out the call with Retentions as that’s the consultant who arranged in.Till to date ,no resolution.Anyone who wants a contract,never with MTN.they are ******,I’m ready to take them to Consumers Ombuds.