Bridge of Contract

I have just realized that the amount that i have being charged is different for the past month from my original amount that i signed a contract for which was R229, but now i have being charged R239.01, i even do not understand how do you sign a contract for R229 and when the company deducts they deduct R229.01, which means if MTN is deducting an extra 1 cents on each of their subscribers they are getting millions of rands **********ly from the clients. This needs to stop the original contact term is for two years for an amount of R229, i need this to be adjusted, you cannot just change therms of the contract when you want and fill it suits you, this is day light ******* of peoples money that they work hard to earn that money.