wasnt helpfull & luggauge RIP OF

Good day,my sister & I checked in yesterday,the guy said that I didn't pay for my luggage & I have to go to the ticket sale kiosk. I told the lady that assist me that all 3 bags together is less than 20kg,she charge me R750. The assistant at checkin asked me why I paid so much & I told him that the lady said I must pay R750. I am very disappointed in flysair the least sshe could have do is the help/assist me. R750 I very much really and I think that was the last time I flew with you.