Mtn
Cancellation of BIS on existing contract

I've been unable to download for a while now on my Blackberry

I went onto the MTN website and the following notice is displayed "Please note that BIS is no longer available for new purchases or customers that acquire BlackBerry devices as of 1 March 2013. Customers can now purchase MTN BlackBerry Absolute or any of the BlackBerry Tiered Services"

I contacted Autopage, my service provider, and they informed me i have to pay for data as my BIS has been cancelled, even though I have an existing contract.
I received no notification of the cancellation but was billed for the service in March.
Autopage stated they are unable to help me as this is a decision made by MTN.

How can MTN ignore their own promise and why do I, as the consumer, have to follow up and fight for what is legally mine?
Surely this is a breach of contract by both MTN and AutoPage?!