I have to pay for Vodacom's mistake!!

I went for an upgrade on the 12th of November, I wanted a new phone with only 50mins voice and 5gb data. I was told that I would have to take the 5gb seperately at R99 pm. I agreed and to my surprise, my original number now has the 5gb and the new sim has the 50mins voice. I need the voice on my original number to open my gate. Went back to the store and they can't help me. Now it's going to cost me money for their mistake!! How *********** can you get?? Why would I want a new number to phone people if I had this number for more than 18 years? Vodacom is just getting worse every year!!