In order to be deductible (and therefore qualify for an Accountable Plan), that trip would need to be a temporary job away from your "Tax Home" (main area of work).
Unless your employer had proof that your "Tax Home" was elsewhere, they could not use an Accountable Plan (which is usually used when you already work for an employer and they temporarily send you to another city to work).
As such, I think they did it correctly (a Non-accountable Plan), and there is nothing you can do.
