Stuck in contract based on false information

I was due for a contract upgrade and visited the Vodacom shop in Fourways Mall. The assistant indicated that I could get a pay as you go second phone linked to a new sim only (dual sim) contract. I signed the Smart L contract (and paid extra for BIS since the main phone is a BB) at the Vodacom4U shop at Northgate, but as soon as I phoned one of the two phones, both phones ringed. I enquired about this and they indicated then that it cannot work. I asked them to cancel the contract as it obviously cannot do as I was told. I had to cancel the sim swap on the second phone as well. They indicated that it is a lot of work and that I should rather have the contract changed within certain conditions. I am now told that I cannot change the contract due to expired cool off time and now I sit with 800MB of data per month on a BIS BlackBerry. Certainly this cannot be the level of training given to staff at two different shops. I did another two sim swaps (all out of pocket) as the Fourways branch got one of the digits on the second phone number wrong. Could someone from Vodacom please contact me that has a solution to this contract nightmare as I am now tired dealing with the shop assistants.