Shapiro shaik's changing balances

My MTN account was handed over to Shapiro shaik. I called requesting for my balance. I was told its 3480. I then paid 2000. A few days later i paid 1500. I then emailed my proof of payment. After that i received an email saying my account is paid up. I then requested a paid up letter. No reply was sent to that email. I then called that same day to ask for my paid up letter, i was told now i owe 400. I then requested to be sent banking details with the statement. The sms with the balance came back showing that i owe 502 now. Which is really confusing and they tell me it's for calls and those calls were made by me to them