Inconsistent information by consultants

I have a contract with MTN, I opted to pay my account cash from around October 2016. From February this year, the account will be suspended almost every 2nd week. We I inquire why the account is suspended they will tell me the account is in arrears, but they are unable to tell me exactly for which month, then they will activate it. Sometimes I will even go to the nearest MTN outlet to supply the proof of payment. On Tuesday the 17th October I called in again to inquire, I spoke to 3 different consultants; one told me that the account was not paid in April 2017, the other one told me that in July 2017, the last one told me that September 2016 and I have sent proof of payments and they never came back to me until today and the account is still suspended. Yesterday I called in to cancel the account I was on hold for 50 minutes and I hang up the call, the consultant who put me through the cancellation department said she has sent and email on my behalf to cancel the account and she told me they will respond in 72 hours. Can you imagine that long to be attended to. What a terrible service, I'm so disappointment with this treatment.