Breach of agreement

I have been told to pay for speding that I have not signed for and my fphone is now locked I took my pacjkage in October where I was told that my package incldes 500 spending limit, there and then I requested the consultant to out it on Zero as I wouldn't afford that, he then confirmed that its done but will oly be applicable in November. I used my phone in Novemeber wuth the assurance that I'm consuming my minutes. Earlier in November I even called rosebank landline to confirm if its now implemented h said yes, you may listen to my call recordings. on the arrival of my bill in December, it was very high and looking t it I was billed for usage. I feel that Telkom is tricking me with the expectation that ill pay regardless. I cannot pay for what I have not signed for. I need my phone unlocked please.