Child in car...

So my mother asked the one day if she could leave my 5 month daughter in the car while she ran into my grandpa's house to heat up his dinner. I told her no and proceeded to sit in the car with the AC on with my daughter. So last night I spoke to her about it when I dropped baby girl off to see her for a couple hours. She seemed like she was going to listen to me.. I go to pick baby up and she fell asleep in the car and mom "didn't want to wake her" so she's in moms car with all the windows up! I'm super pissed off now and she won't be allowed alone with her anymore. My husband was furious. Anyone else had to deal with parents like this? What did you do? By the way, baby is fine. I guess it was ten minutes or so... but honestly. ☹️😑

Edit: windows were up and car was NOT running.

Edit #2: thank you for your responses. I feel validated in my feelings on the matter.