Tourists have been complaining about the refreshments provided at, or near, Pompeii since the mid nineteenth century. The careful Murray's Handbook to Southern Italy warned visitors in the late 1800s to be careful about the prices at the Hotel Diomede (a convenient watering hole near the entrance to the site, just outside): better to fix a price with mein Host before you sit down to lunch; else you might find yourself seriously ripped off.
For the last few decades there has been a decent restaurant in the middle of the ancient city, not far from the Forum. It came courtesy of the allied bombing which smashed holes in Pompeii in 1943 (it had been reported that the enemy was hiding out there). One of those holes was not made good after the war, but found a new use in providing for hungry visitor (plus one of the few loos on the sites). It wasn't ever brilliant -- but it did offer a decent plate of pasta rather cheaper than the modern equivalents of the Hotel Diomede just outside the site.
Then a couple of years ago, it was closed.