Bad management

Today 04/12/2021 I went to exchange one of the items I purchased at ackermans ndofaya mall soweto the item I purchased a skinny demim jean for my son I toke a wrong size the cash was helping me by the name Zandile Khumalo as she was busy with the point of sale she needed one of the managers to come help her one manager was busy at the cellphone counter with two more staff helping one customer trying to rica one sim card fo about 30minites the lines where crazy long then the cashier called the store manager to come help her she came I was not even greeted by her she just came and looked at the POS asked me to pay R30 difference I ask why because I was here to exchange she told me that the item I purchased was on mark down the day I purchased them now they are no longer on mark down I asked why i was not told about this terms and I asked her where in the till slip says I must pay a difference she was rude and not understanding my questions I won't pay that difference coz I was not told that I was offered a discount that I didn't ask for . All I want is that exchange to happen and the staff to be trained more on customer service u can be a manager sitting in your cash office doing nothing one of the staff said I was drunk as I was walking out.