unfair treatment

Vodacom has no respect for its customers because the service is got from themy was horrible.I took out a contract phone early this year and everything was OK till October 2017 when a sales lady called me to say vodacom wantso to give a tablet with R110 airtime and I don't have to pay anything except the R110 for airtime..I agreed which was a mistake,few days later in got the tablet but it was with a smart kicka which meant that the area two contracts. After 3-4 days money was debuted from my account and it wasn't end of month yet and it was not what we agreed on,I immediately phoned vodacom to cancel the contract they came to collect the two phones but to my surprise they deducted another R925 which I went to the bank to make a reversal and vodacom charged me R100 for doing that,so they eventually cancelled the ones I took out last month, they started locking my old contract simcard and it went on for more than a week and I phoned them to ask for premature cancellation on my old contract and they said I have to pay R1844.42 to get out of it.I paid it and sent all the documents they requested but when I phoned them to ask how long it would take for it to be cancelled the lady said I still owe vodacom R389.38 when I asked Sheffield said is for making reversals so they charge me for it.Sheffield wenter on to say if I go and pay R168.99 she would make a service query and I went to pay it.Few hours from paying the second payment is got an sms from vodacom saying they are giving me a credit of R100 which means I still have to pay R129.39 for the contract to be cancelled.Vodacom has taken a lot of my money and I have had enough of it.What can I do?