Over charged for luggage

I am not happy with the exploitation I experienced at the start of my journey. Today was my first time to travel from Johannesburg to Bulawayo by coach and that was used to my disadvantage. I made enquiry on booking about Luggage allowance and was informed that 20kg was free. However when I got to the station I was told all my luggage was chargeable at the cost of R350. When I queried that. A scale was brought and the total weight of all my luggage I was told was 38kg. I was then asked to pay R300. When I expressed dissatisfaction it was reduced to R350 then R200. I must say this is daylight *******, very unprofessional service and taking advantage of customers who are new to coach travel.