Incorrect product

I was sold a wrong voucher that I do not use I buy the same voucher daily in the same store when I noticed that I was sold the wrong one I went back and I was told that I could not change .Why would I go purchase something that I can’t use .all I wanted was a for you voucher and was given a Hollywood voucher to my surprise I noticed it when I was to punch it in my phone. The cashier that was serving me Mushfieqa was busy playing with the her with another collegue.The lady never showed me the voucher she was selling me she just told me the amount that was available.