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I wouldn't get upset just yet, wait until you've talked to the tint shop first. It it's a good shop then they will make it right. If they try to screw you over, then get upset.
I agree with mph07alloy... I understand your concern of damaging your defroster, but since the film was just installed, the adhesive has not completely cured and most likely can be removed by them with little to no issues... Go see them the next day they are open and they're probably more than willing to take care of you.