It’s people like the OP that give SD’s a bad name. Sometimes girls change their mind, or aren’t happy. They have regrets. You need as the SD to be able to read this and act accordingly. If she was disinterested and busy on her phone, that was the time to say: this isn’t working as I intended, let’s call it a day. She’s obviously not into you/the situation if her phone is her priority
Since you’ll be using all the usual security tools - punting phone, fake name, no personal info - then any annoyed pimp or boyfriend or male friend she has asked to put the wind up you - won’t really know who you are or be able to find you. They’ll just be empty threats bourne out of frustration or annoyance.
I said to my son “I’m gonna kill you” but we didn’t make a complaint to the police. It’s just words, in the moment. I think the girl has not liked you, and not known how to get herself out of the situation. She didn’t want to go through with the meet, but you didn’t pick up on that and kept her there for hours. She will have been texting her friend about this, asking how do I get away from this creep. The food break is the opportunity and she leaves, you don’t offer her any money for her time.
She’s pissed off about her wasted time and how long you left her stuck with you. Maybe she thinks you’ll be in touch again. She gets her mate to call you to try to get some money from you for her time. You refuse so he gets a bit nasty, on her behalf.
Instead of calling the police and banging on about it here, you’d be better spent reflecting on how you behaved, why you kept her prisoner in the hotel when it obviously wasn’t working, and why you didn’t offer her any money at all - even a token amount - for her time and expenses.