Contract dispute

Did an upgrade and was given a quote which was agreed on between myself and the agent .All docs etc. were processed. Discovered to my dismay at a nlater stage that the contract was not even close to the one we had agreed.Agent (Vodacom 4umall at Carnival) are not interested in helping. Vodacom customercare are also simply passing the buck backward and forward. I have requested on numerous occasions that a senior supervisor make contact with me to resolve with no joy.