Limit heating time if temperature is not met after specific time

Dear, since a while granny has move into our house, she has taken the down stairs bedroom. But .. she also likes the room to be aired a lot during the day and forgets to close the window in the room nearly every day. My wife and I have taken it up to check on the window each day, but from time to time of course everybody thinks that the window is closed while it is not. During summer this is not a real problem, but in winter time .. the heating in her room starts at 8 pm and stops at 10.30 pm .. since the window is already open tado does not detect an open window of course and tries to heat the room asap ....so the heating is running for 2.5 hours but the temp in the room is never reached ...is there a way to tell the tado valve to stop heating after a certain time is the temperature is not met ? I could achieve this with IFTTT, but since a while they charge like 7 euro a month for a pro account .... any other ideas please? I have the same with some other rooms during winter time.