Contracts mean little at Vodacom-payment change

I took out a 2 year Vodacom contract in April 2014, a R199pm 1GB deal. My wife has been using the contract with me paying the account almost religiously. My wife started getting calls about a week ago about an amount in arrears. <br> <br> I called Vodacom today and was informed that I owe them R35 as they changed the contract's monthly payments from R199 to R205, and that they apparently sent an email at the time. A few problems with this 1) the contract I agreed to was R199 for 24 months 2) I have had contracts with mobile companies for nearly 2 decades and this is the 1st time an operator decided by itself to change my monthly payment amount without my consent 3) I have been running in arrears for the last 5 months, yet the company decides to inform me now 4) I have never received any email regarding my contract from Vodacom 4) The call centre guy then tells me provision is made for adjustments in my contract, now if Vodacom doesn't take the 30 minutes to explain a legally binding agreement it is careless to assume a they dealing with a \reasonable man"which in this case makes the adjustment legally disputable 5) No reason was given as to why Vodacom decided to change my contract!!!"""