Handset /Software upgrade

I handed my phone is at Mtn Trade Route on 13/08/16 for software upgrade , job card no FCEN ********** . On 31/08/16 I received a SMS that I must pay R853.20 .I spoke to Thabo at the repair centre I was told that the screen was cracked (ref no ********** ), the repair centre received the handset on 21/09/16. As far as I knew there was NO CRACKS on the screen when it was handed in. With a lot of calls / emails back and forth I was told by Lerato and Thabo Modise to take it up with the store. At the store I was told again to take it myself to 14 th Avenue and I refuse as the phone was still under warranty. Up till today NO PHONE. I' m paying for a handset / phone that I don't have. I will not renew my contract and will not recommend Mtn to anyone else.