If KEY tours are not operating in November, did you try CHAT tours? Theirs is also good, it's just that you'll have to take a taxi from the hotel to Old Town (and you can share with another tour person) ...
Another possibility is just to DO Nafplio YOURSELF. Take a taxi to the Kifissou Street bus station ( KTEL Intercity bus) and go to the ARgolid window for a bus to Nafplio - 11.5 E per ticket, and it goes every hour on the half-hour. A nice 2.5 hour ride, sit on LEFT side for view of the sea most of he way. When you reach Nafplio (end of the line), take a taxi (3.E) to Hotel Victoria... very handy. Call or e-mail & request a floor with view of the sea or of Palamidi fortress from the balcony. When u leave, knowing the way. you'll be able to walk back to bus.
You can TOTALLY enjoy just being in Nafplio -- get a morning bus, spend the entire day sightseeing this wonderful town, go back the next day. Go to the Cultural Information office (next to Fire Station; ask your hotel clerk). There you can get a FREE audio guide for a walking tour to all the city's landmarks!! At sunset time, head for the harborside cafes... they have plastic sides & heating if it gets cold, so you can enjoy sunset in comfort. Some nice restaurants: Aeolus, Ta Fanaria, Taverna Old Mansion (Palio Archontiko). Lots of great Shopping, the Nafplio Arch. Museum is Superb AND the best Folk Museum in Greece, I think. I did that on my own on 1st trip to Greece and it was easy as pie -- and will cost you a lot less than 120€ per!!