Client Didn't Pay And Is Now Threatening To Call The Police On Us!

Location: New Zealand. This is kind of a long story, we own a home-based dog grooming business, where we do not have an EFTPOS machine, rather, we accept payments through bank transfers or cash. We have this client, I'll call him T, according to him, he has autism and/or some form of mental disability (though he appears relatively normal and is able to work successfully, though that's beside the point), my point is that he is of decently capable mental capacity. He has brought his grandfathers dog to us several times in the past, always taking a long time to pay and acting like he didn't get our messages, however, this last time, he still had not payed for over a week. At this point we sent several messages to him requesting payment once again, to which he essentially responded via email that he WOULD NOT pay unless we responded to his email and booked his dog in again (we were planning on not booking him in again).

To this we once again responded requestion payment as it is his legal obligation to pay for a completed service. After this he messaged us saying he completed the payment, when we then received an obviously phony and fake message on our phone saying that he completed the payment, which we confirmed in person with the bank branch was a fake message. We believe this is him potentially impersonating the bank and sending us what looks to be a phishing email. This is what the message said: 'Hi, ASB here. _________ has sent you $85.00. To collect, visit the ASB website, search Collect and use code code A24MNE before 22/10/2025'. We obviously responded saying that we spoke to the bank and confirmed this is not a real payment and after this, his 'mom' messaged us from the same number saying that we were harassing a disabled person and that if we contacted him again she would call the police and complain to the government for us comitting ablism, and for us to message her instead, to which she never responded and we still haven't received payment.

Now honestly, it's only $85, but at this point it's a matter of principle, I don't want them to think that being disabled means they are exempt from paying for a service, and I want to know what are the next steps I can take? Should I just call the police or what?