Vodacom no service/no signal

For the past 8 years in my office I had perfectly 3G signal. Sins the 9th of March I had only edge (1 baar signal) or emergency calls only / no network service. I called all together 8times vodacom and they can't solve my problem or they don't come back to me as they told me they will do. I want to cancel my data contract with them as I pay for it every month and I can't use it at all in my office. They told my they can't cancel it, the network department must first give confirmation that they can't fix the signal problem and for 7 weeks they can't fix my signal problem or come back to me to tell me they are busy with the problem.