inconsistent service

Bought Samsung S3 mini in December '14. Phone was problematic 3 months later with internal memory running out. Had to do a software upgrade. This have been the trend ever since. every 3-4 months the same old problem. In Jan '15 I was promised the phone would finally be sent to JHBG for scrutiny and repairs. this once again did not happen. However, this time around I was informed that the phone has \water damage"and is beyond economical repair. ONLY Vodacom Tech-zone had ever opened this phone"