PRODUCTS PRICED WRONG

ALTECH AUTOPAGE CELLULAR has given me the worst service ever - 1) I called at the beginning of the month to upgrade my contract - I was given an amount for the package R 1300 - then I got the paper work and completed that and a few days later I called to see what happened then I get told the package is R300 more expensive so I complain about it and get told they will listen to the voice recording - they hear the voice recording of the sales person saying the package is R1300 all inclusive unlimited calls and 10g Data but sorry they cant help me with that as the package is now R 1799. There is nothing they can do and they wont honour what their sales person sold the package to me at.this has taken 16 days to get nowhere and no one can give me a right price for my package...... The Customer service manager told me there is nothing he can do and I must decide what I want to do. I have 6 cell phones on contract with them for my company and they wont help me.... THERE IS A VOICE RECORDING OF THE SALES PERSON SELLING ME THE PRODUCT AND ME ACCEPTING AND THEY WONT ADHERE.....