Rude behaviour and poor service

The game store in gateway mall has such pro service , I purchased a laptop from them on Sunday and I went back in on the following Saturday because the laptop is slow and I was at work and didn't have time to take it back in but they were so rude and unprofessional and refused to let me pay the difference for another one and they refused to give me my money back , all they did was upgrade to windows 10 , such poor service and such rude behaviour