Having covered only 6000 miles since last July I'm not in the least surprised that the oil required changing sooner than at the expected service date. Short journeys and frequent cold starts shortens the life of the oil considerably.
Do you leave the AC turned on all of the time as it is intended to be used, or do you often turn it off ?
With the greatest respect to the guy who fixes Farm Trucks, he's probably not able to listen to the gearbox on your car and come up with an absolute diagnoses of what the clicking noise is.
Trying to change the mileage on any modern car these days is extremely difficult. Sure the mileage on the instrument cluster can be amended, but as soon as diagnostic equipment is connected to the OBDII port you would see the true mileage in the very many different modules that also record the vehicle mileage, and these are very difficult to change.