Unable to repair phone - now I am being billed

I took my phone in to be repaired in October 2014 for the first time as it was freezing/switched on and off by itself. I received the phone back and the same problem persisted. I then handed the phone in again and I received it back with the same problem. In 5 months I returned the phone 4 times, every time I am without a phone for a week or two, currently it is still with Vodacom. Today I receive a call from them to advise me that the phone has a dent on the one corner and quoted me R1,700.00 to repair! Seriously? The problem is still not fixed and the dent is so small and it was there then I took it in 5 months ago. Now they are telling me that the Warrantee does not cover for the phone if it is ****aged in any way! Ridiculous, they are unable to repair and do not want to replace the phone. Now, I, who has been unconvienced so many times, has to pay.<br> I work in the hospitality industry, and I know what customer service is all about. I will definately not recomment Vodacom to anyone. Their customer service to their client has become almost non-existent.