Falls information of a cellphone package

I called in to take out a cellphone contract about a year ago. The cellphone contract i wanted came with free minutes, sms's and data. The data that i was suppose to get was 1.5GB per month. A few months down the line i noticed an increase on my bill and called vodacome to enquire about it. Consultants that i spoke to failed to explain to me the real reason why my bill was suddenly high, instead they told me that it could be the settings on some of my application that are active in the back round and helped me with the settings and gave me a discount. But same thing still happened the following month, i called vodacom again to find out why is my bill still high. All the consultants that i spoke to could not give me an answer, until a sales person from Vodacom called me trying to sell me antoher contract and i told them i have a contract and they said i'm paying too much on my current cotract because my data allocation has changed from 1.5GB to 200MB per month. Now this explained why my bill was suddenly high. I decided i'm not going to pay for the cotract anymore because i feel cheated by vodacom. I received a notification of termination and demand to pay the otstanding amounts.