Call the store and ask for Customer Service. You didn't say which location, but it will be easy to find a phone number if you Google Safeway + [your zip code]. They'll do their best to help you. If you used a debit or credit card the bank or credit card site may be able to help, but it will take longer.
If the order was placed online, you probably have an online receipt. If you have an order number they may be able to print a receipt for you at the store. But most likely if you did it online that's probably where you receipt is, you could also check your email. I'm not entirely sure though, that's just usually how other stores work. Hope this helps.
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