Change of contract package.

I signed a contract with Vodacom on the 30th of March for the Alcatel Idol Alpha deal for R99 pm. The store(vodacom4u waterfront) didn't have the handset so they ordered it. On Tuesday the 7th of April as i was fetching the handset all was well, the consultant showed me the device then one of the other consultants said the price had gone up as there is a deal for R300pm now. The consultant said she'd call(I'm still waiting). I signed for the R99 deal before there was a R300 deal. please help.