Hot water -what not after 10 at night

We were thinking the hot water tank was going bad because when we went to take late showers the water would go cold. Land lord came by and explained German hot water customs. they only have the hot watere tank heat water from 5am-10 pm. well we didnt know that. so now it is fixed electronic sensor had to be set to 12 so now we always have hot showers. they cannot adjust the 5 am time just the other end. By the way, it feels like we are going through the ever expensive Oil very fast. remember to fill all 3 bins it will cost 3000 euro, we are going to fill up yearly instead of at end when they are all empty. I am constantly turning off heaters in the house which is funny since i usually want a warm house.