Overweight Bag

I recently traveled from Vanderbijlpark to mossel bay with no problem at all, but the check in was a total disaster. Without any acknowledgement on my ticket or on the booking website we were told to take our bags to be weighed and we should pay how much our bags are over weight. I then asked the lady why is mossel bay the only place the weigh bags and why should we be the only ones to pay she then said if I don't pay I must leave my bags behind. With a sour mouth I payed my overweight bag and climbed on the bus. On the return I made a fact to check every stop and low and behold NOT 1 person getting on payed for their overweight bags and I could tell by some bags they were really overweigt. Could someone from head office please contact me and explain that to me.