I would recommend you write (email, although a letter will get more attention) a letter to TPWD HQ because that's total bollocks. One, there's nothing on the coupons to tie it to the State Parks Pass it was issued with (name, barcode, whatnot). Two, they're engaging in not just poor customer service but ANT-customer service with attitude.
You should also call the park and ask to speak with the supervisor to lodge a complaint about the particular TPWD employee who verbally dressed you down for something as simple as a 50% off camping coupon.
Ridiculous!
