Sales under false information

Their marketing partner phoned me and sold a new data contract to me i asked her if my number would stay the same about 2/3 times and she repeatedly said yes it will, i then opted in as i was spending a lot of money on extra data, but i only said yes because my number would stay the same the sim card came and that number changed and wasnt my old number. I then phoned them and asked if i could share that data with my existing contract and they said no i cant ive ever since spoken to almost 12 agents to cancel that contract but nothing is happening. They send me up and down and isn’t helpful at all...this month they have deducted R1077 and seems at ease not to give my money back