I know someone who has them in self serve bays. I thought he was on here, but I can't find his profile. He told me that some of the features that they promised do not work yet. It seems like there was another issue, but I can't remember what it was. They worked it out, IIRC. From what I gather, they can't do count up yet, and they do not have a
vending machine solution. It seems like every product they launch these days has issues. Are you a member of the Dencar Car Wash Innovators Hub group on Facebook? There are over 500 members on there, and I'm sure you will get a better response if you ask the question there.
https://www.facebook.com/groups/1311476170236327