Hey we all have made mistakes in one form or another at our jobs and no-one is perfect. As long as they know that its unacceptable and if they do it again, you'll take your business elsewhere. The best way to hurt some is not with your mouth but your wallet. Money is money. Let it go this time and give them the benefit of doubt. If it happens again then you have every right to call the BBB or contacting the local news. I firmly believe in giving someone a second chance. If everyone didnt do this there would be angry people everywhere. Best way to solve this is doing the oil change yourself because when you do it, you know it'll be done right and to boot save some $$.
I did not say go to the BBB, write the auto mfg, go to the papers, etc... JUST because they made that error. I did not say that. I said to do it IF they refused to refill with Synpower. Big difference.
If it were my vehicle this happened on, which would have Royal Purple in the crankcase, and they did an OC using regular conventional oil, the only way it would be made right for me is a refill with RP. Nothing else would be acceptable. Even if RP had conventional oil it would not be acceptable if I was running RP synthetic that they changed on their own. If they refused to do a refill with RP I would take steps to make sure they paid for it so to speak. THAT is what I was talking about.
I agree mistakes happen and you need to give the place a chance to make it right. However, what makes it right for different customers can vary. If I were the OP Synpower would have to be used or it would not be right. Valvoline conventional oil, while great stuff, is not Valvoline Synpower. The OP had Synpower in there and did not request/authorize they change it. Therefor, the only right way to remedy the situation is to put Synpower back in. Period and end of story( for me anyway ).
If they refused then I would take the other steps I mentioned above.