Jan, I was just thinking the same thing.
I can understand, and share the OP's and others' frustration and discouragement with being told by 911 Operators that nothing can be done without an Officer witnessing it.
If the Operator(s) are giving the info as a caveat, that's one thing. But, if they are informing the Caller of that in a tone of voice/attitude suggesting it's a waste of time to report, that's wrong, IMHO.
I don't know if all 911 calls are archived indefinitely, but I would encourage folks to keep calling and (hopefully) get a longtime, or permanent record of each incident, and/or report it online, if one of the online reporting options allows such.
Then, if word gets out to our Officers on the street, they can keep an eye out for the Escalade, especially in the area(s) of repeated incidents, and maybe inform the driver it's not cool to take the term "Escalade" too literally....