Disguss in service and false information

I would like to report my UTMOST disgust in the level of service I received from Altech Autopage, Cape Gate. On 24/7/2015 I upgraded from my Blackberry Q10 to a LG4. Upon discussing the contract I specifically requested that I would like my contract to be less than R500 per month. I pointed out that with my upgrade in 2013 I was not informed that I would pay an extra amount of R148.24 for my device. I specifically asked if this will happen again with my upgrade to which I was informed that my account will be R655.42 for the next 4 month after which it will be R486.43. I was informed that to have my account less that R500 per month, I will have to move from MTN Anytime 350 to My Choice 100. I was told that I would receive 100 sms and 300MB data. I specifically requested that the additional 500MB be added as well and upon this, I signed the contract. On 19/8/15 I received my ***.88 I'm being charged for monthly device payment for the Q10 and the LG4. I was told that the store manager informed me incorrectly about the data although she gave me everything in writing. The data that I had left AND paid for is also lost and that's unfortunately how the new contract works-LEGAL?