MTN contract stopping me from porting to Vodacom

I have used the same phone number with MTN for over 10 years with no major network challenges like what I'm experiencing now. In Dec 2014, I moved to a small township called Nokaneng, about 45km from Steelpoort on the R555 road. Each time I get a call, I battle hearing the other person on the line and vice versa. This has impacted negatively on my life and continues doing so. I reported the matter to MTN and they exhausted their options and were to send their technicians to me within 3 working days since the 8th of Jan 2015, (***) till this day, nothing has happened, my struggle continues. I miss important calls. The only option I am left with is porting my number to Vodacom as their subscribers never seem to have these issues but I can't as I have a contract with MTN, a contract that is ruining my life. Meanwhile they continue debiting my bank account for services I am not getting when I desperately need them.<br> If I stop paying, who gets blacklisted? Can I get assistance in this regard? <br>