This is absolutely awful. Sadly not uncommon. Some 15+ years ago when my DD was school age, the same sort of thing happened. Quite a number of times.
One of her friends would come round after school, say half three, four o'clock... And we'd say at about seven o clock (after doing a meal for her with us by the way!) 'Right, you've got to go home now, Gemma. Can you get your mum or dad to come and get you?'
And she'd ring and 'mum' wouldn't answer. Neither would dad. Tried two or three times, she still wouldn't answer - either of them. So we ended up driving her round to her house because we lived 2 miles or so away from where she did, and it was late at night. We would drive the two miles and her parents weren't in. 
So we had to bring her back home and quite a few times it would be 9 and 10 o'clock at night before the mum or dad came round. No thanks or apologies or anything. 'Come on Gemma... Get home to bed.' No thank you to us or anything for feeding her, and looking after her for six hours. Fucking unbelievable. This happened quite a number of times with 4 or 5 different girls who were friends of DD. These friends ALWAYS wanted to come to our house too, and rarely did my DD go to theirs. Maybe one time for every 10 they came to ours.
And their parents NEVER fed her, and NEVER had her there for more than 2 hours before turfing her out. Also, we took about 6 or 7 different friends on several day trips every year over about 10 years. Only ONE took DD, just once, to Alton Towers. ONCE. We must have gone on 20 daytrips with 6 or 7 different friends of DD over about 10 years. She is an only child, so we wanted to encourage her to have friends, and have friends around to play, but some parents took advantage and took the piss - and as I say, they very rarely had my DD around at theirs.
The shit hit the fan when this one woman sent her daughter to ours about 3:00pm on New Year's Eve afternoon. My daughter said, 'oh please mum, can Sarah come round? Just for 2 or 3 hours?' I said, 'well yes ok then, she can, but she's got to leave about 6pm because we're going out for New Year's Eve.' (We were going to my cousins party.)
So six o'clock came, no sign of Sarah's mother. 6.30pm 6:45pm no sign of her mum and I was fuming... Sarah rang her mum, and so did DH... no sign of her. So Sarah rang her nan, who lived not far away. No sign of her, and no answer. So we drove around to her mum's and her nan's, and her auntie's, and a couple of her cousins. (All within 2-3 miles but took about 40 minutes!)
Amazingly and surprisingly, not one single person answered the door. 8:00 o'clock at night and we were supposed to be leaving for a New Year's Eve party, and I was absolutely fucking steaming by now. I rang and left a message on her mums phone saying 'Come and get your daughter right now, you've got 15 minutes to get her, or I'm calling the police. Because you're literally abandoning your 13 year old child here.' (And I swear to God I would have called the police as well.)
10 minutes later, I was 5 minutes away from calling the police, and the mother came to the door, so she couldn't have been far away! 'Come on then, Sarah!' she said. And stormed off away from our house. Didn't say sorry to us or thanks for anything. Just stormed off.
It's fair to say that the air was cold between us every time we saw her again. And it wasn't that long before she started to turn a couple of the other mums against me, and 3 or 4 of their daughters turned against my daughter. It was quite an uncomfortable time for about 6 or 7 months. I did nothing wrong. I just acted appropriately against what was absolutely fucking terrible parenting.
Calling the police may have sounded extreme to some, but this was the tip of the iceberg and the straw that broke the camel's back. Had happened multiple dozens of times and I had had enough. So had DH. We had looked after other peoples children more than anyone else we knew for YEARS. We didn't let it happen again after that, with ANY of her friends. We had tolerated it for about 9 or 10 years at that point, but the New Year's Eve thing was the final straw.