Buderus R2107 Water Heating Issue

Dsleep

My father winters in the south and usually shuts off DHW while he is gone. We also shut off his well pump in case of freeze up. We turn it on once a week to make sure pressure stays in boiler at correct level. The R2107 is changed to shut off DHW production. The screen reads DHW off and the moon shaped light stays on. When I arrive the next day the DHW shows 180 degrees even though the DHW is A: supposed to be off and B: set to 135 degrees if it is on. I have shut it off about 10 times now and had the installing professional do it once also. I can't figure out why it won't stay off and why the DHW production is 180 degrees. It has been cold as heck here Outside temp 0 today, boiler temp on auto is running at 210 degrees. Thanks