black berry 9720

This is my 7th complain and 7th exchange phone I received from Vodacom, with the same problem. The handset is faulty and need to be withdrawn from the market. The phone keeps on cutting out on the network, freezers all the time with a 20 min intervals. Aftter a phine call, it just cut the network. I am tired of Vodacom and this phone. Shall I approach the Consumer Commission ....cant deal with this