Call centre confused staff hopeless

Took a contract over the phone and was advised to port my number and then I could call and move my number, now wen I call the consultant says and cant do that coz I should have done that before the fone came to me, i have ask her to cancel the contract coz i did not even use the sim card or any of the benefits, mtn should send staff for training so all can help customers, really disappointed with mtn, 1st time using network and all ready such a bad experience. All I want is to keep my number. Note I have not inserted the sims that was sent to me as yet. The store says I should also fone call centre.