Did you check if the ‘Location’ you set is correct? The controller uses your location to obtain time zone automatically, so if the location is incorrect that will result in the time being different.
So far it seems the advice you sent me in the support section is correct.
It was the CR1220 battery.
I have left both units running for 3 days so far and the date and times are remaining correct.
If anyone else has this problem, the battery in the OS i have was difficult to see, i had to remove the display which is attached with pins into a socket on the mother board, It wiggles out easily.