high bill and billing after clear instruction not to bill when free data finished

I acquired a cellphone contract through telkom in January 2018 and my sim card was only activated on the 24th of January. the contract includes a cellphone(J7 prime 16G), 500 MB, free IM texts and call, free calls to telkom numbers and free calls to landlines for R189 pm and i gave a clear instruction that as soon as my free 500MB is finished telkom should cut me off and not bill me. I was then told by the sales person and also by communication that telkom on 16/01/2018 they will deduct R189 from my account and indeed they did deduct the money in my acccount. i phoned telkom and spoke to a lady called Nontlantla and she told me the R189 deducted from my account will be reversed as this was a way of checking if there was money on my account and my bill and benefits will be pro-rata as i was only rica-ed month end. this month i receive an account of R432.27 due 28/02/18 an amount i cannot afford and i did not agree on. i took a contract of R189 because that is all i can afford pm now telkom is exploiting me and sending me high bills. i phoned telkom saturday morning and spoke to a lady called Lesego and she tried to explain the bill but still it didnt make sense to me and was not what was agreed upon when i took the contract. to make matters even more worse telkom billed me after i clearly instructed that i dont get bill after my free data is finished. Lesego also told me on saturday that my 500MB for February was still unused. that is not my only issue telkom gives me 500MB pm and on saturday evening i get a message telling me i have only 94 MB left for the month. i need this to be urgently attended to or telkom must terminate the contract, take back their phone and ill go to another service provider as 500MB with mtn used to last me for a whole month.