Do I really need to start negotiating at the till?

Today again at the till none of the buy one get one free items or less 25% items scanned .So after telling the cashier then he goes and checks and comes back and then only calls someone to fix it at the till?All the kids shoes were less25% ,not the one's we bought apparently?So after almost an hour at the till for two Tom Taylor pants, my daughters dress and panties we left her shoes.I asked to speak to a supervisor or manager and was told that they left already , the lady I asked only left to never return pretending to call someone else.The new look edgars is great ,just a pity the staff attitude is the same.Please ensure that the promotions are loaded onto point of sale deacon.