We haven't had that problem with our 2012. I would bet there are some of those thermostats still in some repair guys hands. I would remove the 2 screws holding it to the wall and get the numbers off of the Thermostat. Then look on eBay and google to find shopping results. Many of the newer digital Tstats do have both Fahrenheit and Celsius modes. Usually pressing a button for a determined period of time will change those back and forth. This old of one probably will not do that.
Chris & Maria
2012 36RL, Full Body Paint, Dual Awning, Dual a/c, Splendide Combo, Fisher Paykel dishwasher, 6.5kW Onan, Goodyear G614's. 2015 F550 6.7l, 4X4, Lariat, CC, 176" WB, Long Box, B&W Companion