Wrong size

I went to pep in kimberley northcape mall...first there was a long queue because only 1 till is operating and its month end...I quickly got what I wanted,as I know my size and what I want...stood in the queue,paid and went home,got home and there I held the pants that I bought in front of me and it looked very small from the size that is on the label...than I saw that,on the prize tag it shows 40,on the sticker that is pasted over the label it shows 40 than I saw the sticker can come off and under the sticker it shows 10...really,and I can't take it back cz pep is already closed as I was in a meeting till 18:30 and I have to wear the pants tomorrow for my first day at work,had to phone my boss and ask her if I can wear a jean which is so unprofessional...no really man