As jimfitzgerald says, the ETF is 175-$5 per month. It sounds like you have paid for 20 months, so the ETF really should be $75 rather than $150. It's probably still cheaper to pay for the remaining four months, but depending on taxes etc, it might not be all the different.
But..., you are also right in the title. Verizon doesn't (and in some sense can't) value individual customers, although they and every business claim otherwise. Unless you are a large corporate account (who may spend in the millions per month) your revenue stream is totally unimportant. Now of course aggregated over the 90+M accounts, this is what makes the Wireless part of Verizon live, but nearly all of the individual accounts are too small to make it worth while to even think about making exceptions.
A good analogy might be a toll booth. If you are lucky, the attendant might smile at you and wish you a good morning or evening, but try to explain you and your family have used that road daily for the last 10 years and you just want them to give you a break this time.... Well, good luck! And the reasoning is the same: if you decide to stop using that road (which might or might not cause you some problems) then that's sad for the toll road authority, but not very sad, in fact not sad at all. Other cars will be along and your revenue wont be missed.
So, in the same spirit, always evaluate your options with other providers. The companies are not really loyal to you, and there is no need for loyalty the other way.