Upgrade Issue Technical Glitch

End of May went to the IStore Menlyn for my Vodacom Upgrade because I was informed that the phone I order online was not available and should go in store. To my surprise the Store did have stock, strange. Any case not the problem. Did my upgrade got my phone, happy. Last week I got contacted by the Store saying there was Technical issue they had when upgrading my contract the info was not send through and now I need to pay more because the contract I choose is not available at the price that I was given. Really who Problem is that, mine??????!!!!!!!!!