Stinking attitude from the manager

I bought kellogs Cirnflakes at Game store in East Londond.they were on sale for 120 for 2 1,2 kg.guess what when i opened one today it is rotten.the expiery date is 17/09/2022 What makes me writevthus review is the attitude i got qhen i get to the store.the guy by the name Sneldon game me a stinking attitude.he told me there is nothing they can do without the slip.i mean who keeps the grocery slips for about a month.he didnt care.thats his attitude that makes me wanna puke.oh so help me God.