Not complying to the agreement

I really did not want to take this sim contract and they kept on convincing me how it would be my benefit but now I am not what was promised to me. First of all I was told my monthly installment will be R149 yet am not paying that amount, secondly I was told I'll have night owl yet it does not register on their side when using the services let alone when am out of anytime data their services like YouTube data doesn't work at times.