Bad service

I am very disappointed with the level of service offered by Vodacom. I upgraded my contract May 2014 and from March 2015 had a problem with my handset. For the past four months the Vodacom Repair has tried to repair the Handset, but with no luck. They couldn't repair the original handset and replaced it with a refurbished handset, without notifying me. I had only seen it was a refurbished one when it was sent back to me. Vodacom wants me to accept another refurbished handset. I don't think that is fair considering that the other refurbished did not even work for a day, the contract is a year old and out of the 12 months the repair centre has had it for a total of 4 months. I am paying for a handset that I don't even have.