Vodacom is *******

I have been with vodacom for about 20 years and had no problems in the past, but recently I have had so many problems with them that I want to cancel my account with them, but every time I call to cancel they say that my account is in arrears and when I call accounts they say no they just need to update the status. I went back and forth several times with them and are still unable to cancel. I even went into the store and they told me that I need to phone the call centre. I have had it with them. They have even blocked my sim stating that my account was in arrears when it wasn't. I refuse to pay them until this gets resolved and will be moving to Cell C.