Could not use my smart shopper coupons

On Saturday we did our shopping at PnP N1 city and decided to buy the items we could use our coupons on. When we paid the coupons would not scan. The lady who assisted us swiped our smart shopper card 3 times and rescanned the coupons which still would not work. We double checked the items we purchased and they the correct items. She rang for a supervisor which we waited over 5minutes for and held up everyone else waiting. They lady assisted us also had to ring more then 5 times for a supervisor which never pitched. Eventually we paid full price for the items and left. This is absolutely shocking service from PnP. Also, this was not the first time a supervisor was unavailable. Its really shocking to see them all hiding in the offices making small talk and the client has to wait. Really upset that we missed out of discounted shopping this week and actually paid more for our items purchased.