Cellphone Contract

I took a contract with Elite Mobile which they use Vodacom as their service provider. there is no customer support on both companies. I have been trying to contact Elite Mobile and their phones keep on cutting, they don't even try to call me back. what I get debited for is not as per the agreement and worse this month they have double debited me. I don't want this contract anymore can they collect their phone package and if they don't get back to me by the end of Business day Tomorrow I am going to reverse the debit order and stop them from debiting my account.