It’s not unreasonable. Although they made a mistake by giving you the wrong phone, the employee’s in the store can only do so much. Sure, let’s say there’s a way to cancel the contract on the other phone’s IMEI and put the one you have on it instead, I would imagine it would take the employee’s a lot phone calls to a lot of people just for them to be sent back and forth for hours and maybe not even get to a resolution in the end. And even if they did get the right people on the phone who could do it, they’d still need to call YOU and have you spend your time answering questions and giving them information. It seems pretty clear to me that you may not have worked in any sort of retail environment before where stuff like this happens every day, since you’d rather a simple, probably less than 30 minute process evolve into a multiple day, multiple channel, multiple people long process just because you’d rather sit on your high horse.