Poor Product Knowledge Incorrect Billed

I signed up for the promo 20mbps LTE mtn fixed but the charge me R499 instead of R299.The consultant MBALI.M is unable to understand that they are billing me wrong. I already have another 50mbps LTE deal that I get the discount for R699-R200, so they charge me R499 which is correct. He then wanted to cancel my contract that I did not even say I want to do. He then told me the promo is only for new customers but how was I able to get the 50mbps with the promo discount. He then later said its shows as R299 but yet fail to understand they invoice me the standard tariff R499 I have been with Web Africa for 14 years, but I can tell u service is pathetic. They fail to understand their own deals.