Poor service from MTN - Sony Xperia V

I have had my contract taken over by MTN. Currently have a Sony Xperia V and have sent MTN an email to complain that my touch/sense on my screen is busy giving in (only had this phone for 16 months) <br> <br> Its unacceptable for a phones touch screen (with no other options available to use the phone) to give in before its 2 year contract expires. Or to give up in general so early....<br> <br> I have had someone from customer service respond to my email and send my complain on to [Email Removed] only to have this email come back as a failure...<br> <br> I need my phone sorted out as i require it for work purposes.