Not adhering to their promise

I upgraded my contract and received a Blackberry Z3. 6 days later I took the phone back as it did not have memory. The consultant said that within 3 days I will be contacted. It is now the fourth day and I contacted the store only to find out that they are still busy with the phone.<br> I requested a new phone and was told that they cant give me one.<br> In the mean time I have to pay for a contract that I cant use due to VODACOM.