Poor service

Really disappointed with the poor service I received today, I bought a formal pants on Friday last week at the branch in Smith and broad street to wear to a function I attended the next day, before I could get to the function the buckle fell off, I had no other option but to replace it with a safety pin. today I decided to a return it to the closest store to my work place in West street during my lunch break. I spoke to the security and explained to her that I had no slip or tag because I had fitted it on in the store with no issues, she allowed me to enter there after I spoke to one of the staff in the store just to be certain before I could join the queue , he told me that I could exchange or receive a voucher as I was pressed for time and could not go check for another one, I joined the queue and stood for about 30 min only to get to the till and told by the store manager that I would not be able to be assisted as I need to have the slip because it's a reject. I do not have the slip because the function was away from home and I fitted the pants on in the store with no issues, now I'm stuck with a band new pair of pants which I cant use again. Kindly assist!!!!