Incorrect billing and runaround

After upgrading to the explorer R2000 was debited off my account. I hadn't activated it as yet and was informed that I will only be billed for it once it's activated. I was told that I had been billed for 2 months explorer as well as my normal decoder. I received the explorer in February. I have called 5 times to try and rectify this and have spoken to 3 different supervisors. The one responsible for this department promised to listen to my calls and call back before the close of business yesterday and never did. Now I can not get through. I've been advised to do various different things like reverse the payment however I do not want to end up with an even bigger bill. Nobody is assisting me even though there has clearly been more than one mistake on their part. I'm beyond frustrated.