Contract cancellation

I did premature cancellation of contract with Vodacom for data bundles , they send me quotation for money I should pay which i did pay the amount on the 15 may . I send back the documents they requested with proof of payment . I call them several time to cancel the contract even now they send me from pillar to post. I call everyday the consultant tell me it will be cancelled by the end of the but its still not cancelled even today. I am tired of this .