At the weekend was out with my 6mo for most of the day so bought a couple of small premade bottles of c&g stage one. Only one got used but the other fell out the changing bag and I've only just found it in the car today. Bearing in mind it's been really warm (about 18 degrees) everyday and the car hasnt moved since sunday would you use the milk or throw it out? Bottle was sealed and unopened. I can't find anything on the bottle about a maximum storage temp but temp in the car must have been hitting 25 degrees at least.
If you can spare it and don't mind it going to waste then you could chuck it. I imagine though that as they don't have to be refrigerated then it is probably still ok. In some countries it would be that warm anyway in a kitchen cupboard.