Extremely poor service...what did I get myself into?

I went to Telkom at Jabulani mall to buy a phone contract...6 days into the contract I returned the phone because I was not happy with the features....I was assured that the contract will be canceled and will only pay for data usage in July. The bill came and I had to pay. Now this month my bill says I must pay R700+ . What nonsense is this...is this how Telkom rob people because I regret myself now I should have continued with my network provider which is mtn. NOW I have to pay the money that I do not have because of stupid sales agent who are chasing commission.