******** price increase

I have received an sms yesterday afternoon from Vodacom advising me, my R135.00 will increase to R140.00 And get an extra 5 minutes calltime. I have got 2 prepaid top-up contracts and will need to pay an extra R10.00 towards my contract which will end in 4 months time. And I will move to another service provider. I have spoken to Peter from Vodacom call centre and I have explained to him I have signed a fix contract for 24 months and not interested in paying a cent more on my contract. I cannot afford this increase. And according to Peter I will have to pay this increased amount. I have spoken to him very I-rate and advised him nowhere in my contract does it stipulate that my contract will increase months before my contract ends. Ive advised him I will take this up with ICASA and Peter then indicate this have been apprpved by ICASA. I have advised him I'm not interested in paying a cent more towards my prepaid contract if I need more airtime will buy extra prepaid vouchers. Vodacom is using this tactic on all their Vodacom customers out there, whithout their concent. It is ******** practice especially when myself as customer do not agree to this. Especially on a prepaid contrac