MTN violates my rights to choice by making it impossible to cancel contract

I've moved to the US and had an MTN contract that long passed the 2 year minimum. MTN call centre makes it impossible to cancel a contract internationally since I can not just call the 135 (even trying +27 83 135 or other numbers I found on Google does not work) I tried email but after many days of delays they led me to the retentions@ which says the ONLY way to cancel a contract is through a call. I have no intention of paying the bill for the last 2 months because this has been running longer than that.