Costco 90 days return

I bought my s7 on march 12, and I am still waiting for the bogo card. My s7 has a few problems and I think that I will exchange it since I am still within the 90 days return(Costco). Had anyone that bought the phone at Costco try to do the exchange before? Also, should I wait for the rebate card to come first before I exchange the phone?
Thanks

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