Lying to the customer to get them to cell c

I'm very disappointed. I went to Sandton branch to do buyout contract. I've been promised R20k for sure and was given a gift card. Was told by a sales man that the card will be activated as soon as the number get ported. The next morning I went to check if it was and been told that they a proving only R10k. I wasnt told that it still need to go for approving. I've been told it WILL be R20k. Now I had to pay balance for vodacom, I lost airtime, I'm loosing on the phone I planned to buy with this cash and I'm very cross. I'm going back to vodacom. I need all my money back that I lost by moving to cell C! !! The manager trying to help. But we getting nowhere. I need what I've been promised!