Vodacom selling faulty phones and shifting blame.

So today I went to pick up my phone from repairs at vodaworld midrand. To my surprise my phone is not fixed and on the status report of the phone they declared that my phone was opened before and that there is water damage to it. I am highly discussed with vodacom, 1. the phone im using is a sony experia Z1. 2. Never in my my life have i tried to open this phone or bring it close to water, this phone still has all of its original screen protectors on. the first day when i got the phone, it went into its phone cover with all its screen protectors and back screen plastic protectors. 3. i pay more or less R3000 each month for this contract Im on the red advantage package. 4. according to my knowledge and vodacoms my phone is still under grantee. 5. Vodacom refuses to let me do a pre-meture upgrade, 1st i was told i can get a upgrade only in December, then when i booked my phone in at the repair center last week they said i can do a pre meture upgrade in 2 months time, then today when i picked up my phone they told me again i can only pre upgrade in November, and once again another sales consultant told me i can do a pre upgrade in a weeks time, so whats going on!!!?????