Refuse to cancel since day 1. Not accepting retrenchment letter.

Been trying to send retrenchment letter since April. Been having issues with vodacom since day one and now this. I refuse to make payment as terms and conditions keep changing ever time I call they want me to pay a cancelation but the cancelation Includes all 24 months or all remaining months but I don't get the airtime. Been trying to cancel since day 1 and been told to go to game them vodacom then call center see previous reviews. I had the right to take it back within the 7days when I already didn't receive the airtime I'm supposed to this been happening every month since. I'm not paying R3000 for a phone worth less than R1500 I'm not paying remaining months u less I get airtime for the remaining months.