Outstanding money on prepaid service

We moved end of June to a new town. With all the hassle of moving I didn't have a chance to phone dstv to disconnect my services and by chance someone phoned me 3/4 of July to arrange a debit order and insurance. I told the person I spoke to that we moved and won't install the dstv this month if they would please disconnect my service. A few days went by (thinking the services was disconnected) when I received a sms stating that I owe R790. I went on to the self service web page to see if the account was disconnected and it was. Now I keep on getting phone calls and sms's stating that I owe DSTV money. As far as I am aware this is a prepaid service, if you don't pay, they disconnect your services. When I spoke to a consultant this morning they said the account was active until the 15th of July and there is no record of someone phoning me. If this is a prepaid service how did they keep the account active until the 15th? Nobody I spoke to is willing to help me with this account, they just keep on telling I must pay this, because it is policy for the account holder to phone in to disconnect although someone for dstv phoned me and I asked them to disconnect my services.