UPDATE: So I finally heard back and managed to get a partial refund of $14.85.

They babbled on and on about the reasoning behind only refunding that much. I feel partly victorious even though it's now officially not worth my time to continue this.

The bottom line is these guys are a borderline unethical business by taking advantage of something the driver has no control over. The GGB system is otherwise great and I applaud them for going cashless. Rest assured I'll use their advanced payment thing next time so PlatePass never again gets a dime of my money.