No network access

I have been on a contract with Vodacom from April 2015 and I had to do a sim-swops in the 5 months that passed and pay for the service even though the network was responsible for this error. The network was off and I could not make any calls or send out messages, the only way I could connect is when connected to Wi-Fi, when I went to the Vodacom shop they could do nothing and could not tell me why this happened they charged me for the service provided which I feel is not fair. The fees also increased from May 2015 and there was no indication of this in the contract when signed.