Dissapointed and unpleasant experience

I visited the absolute pet store in Cavendish earlier today 18.12.2019 I always purchase from this store because of the friendly staff, however since the older staff left, I came across fairly new employees... nevertheless, I made a purchase of 2 x 3KG Iams cat food and I had two Iams vouchers that I received. The consultant by the name of Ann wasn't very pleasant, firstly she did not know how to add the vouchers onto the system, of which she asked another lady for assistance and she didnt know either. The store was extremely busy, so I let Ann assist another gentleman in the same interim I emailed my Iams vouchers to the Cavendish absolute pet email. She kept saying it wasn't working and getting very annoyed with me, also she had clients queing to pay... I then said ok let me email the vouchers again. I then said to Ann, click on your refresh button on your computer, she said it's not working, nothing is coming through. I was getting irrated as she kept repeating herself and not trying to come to a solution. I find my shopping experience this time around very upsetting, as the consultant did not make me feel very pleasant. I never had this problem before, it was always a breeze trying to process these Iams vouchers. I always try to come back to this store and I drove all the way from Greenpoint to the absolute store in Cavendish, and to receive this level of treatment... I'm disappointed and very upset.