99 Cents Only Stores review: Exchange policy

2 days ego I bought by mistake 3 cans of cream corn and I want whole corn. I came back next day with receipt to exchange. The manager Jessica told me is no exchange, all sale are final. I was very surprised because I go to this store for many years and I know very well the exchange policy. She told me too to go to other store. Wrong, very wrong. I think she need more training from company how to deal with customers in those kind of situation. Very unpleasant situation just because the manager Jessica has no idea of company exchange policy.