No one can make a decision

I took my I phone 6 in for repairs at vodacom Alberton repair center. The following played out as i expected as they dont care about a customer. My I phone started giving me problems around October 2015, note at this point the phone is only 10 months old. I did a software up grade and straight after that the speak became very faint on the phone. I battled along with the phone using earphones to speak as i used it for work and e mail and could not hand it in. Took it in January 2016 for the speaker issue and also that the front cover was lifting and the battery not holding a full day, they check it and then sent it for high level repairs. They came back with a R4444.16 bill for repairs for a phone under warranty. I am refusing to pay it, they also blaming me for damaging the phone. they say it has been dropped. Can you explain this? Speak faint after software upgrade. Why must u pay for a phone under warranty? My House hold bill in 24 months is around R90 000. But no one wants to help! Now they want to send be a rebuilt phone for a new phone replacement. How? Where in the vodacom contract it tells you that you get a rebuilt phone and you must have a cover for protection on it!!!