A months notice required from me

Called Vodacom in March to cancel one of my contracts they told me I can only cancel the contract on the 13th of April. I called them on the 13th the lady cancelled the contract but then told me that the contract will only be done by the end of JUNE??? How does Voda**** justify demanding clients give them a month notice for a cancellation but then they can still take two months worth of payments after cancellation?? In my opinion the contract/service should be stopped on the 13th of MAY and last payment should be deducted end of MAY. WHY THE HELL SHOULD I PAY UNTIL THE END OF JUNE? I am going to cancel all the vodacom contracts we have and go to another service provider as I am sick of Vodacom and their greediness! oh and FYI your email bills don't open never have and probs never will.