Suing them will take lots of time, money, and stress. I would call the office and get a feel for what their hierarchy is. Find out which people are in charge and sit at the top if said ladder. Call them and tell them " Hey, it been (fill in time here) and I still don't have my permit. The law clearly states (fill in and cite law here)."
Be kind (who wants to go out of their way to help a jerk?), but be persistent. Call often and write/e-mail the head honchos. Also, I have found that most people will feel at least slightly personally responsible if you get their name. When you get them on the phone ask their name (even if they give it to you) and ask them to spell it for you (even if the spelling is obvious) so they know that you are taking note of their name. When you call back ask to speak to the same person (again, preferably somebody with some authority).
Be kind though. Give them a little ego boost and they'll be less likely to be a jerk to you. Something to the effect of "Thank you Mr. Smith. I have confidence that you'll take care of this problem for me." Using their name when you talk to them also provides more motivation to be personally accountable to you. Who wants a ticked off customer running to their boss saying "Mr. Smith sucks at customer service and failed to fix the issue."?
Most people will fix your problem just so you stop annoying them, no legal fees, attorney, or undue stress involved.