When you increase the temperature limit between 25-30 degrees ?
There are several reasons for the maximum limitation of 25°C.
You can enter an offset to trick the thermostat into thinking it is colder so it would heat longer (doesn't work in the first noted situation though), but it would be more advisable to instead wear warmer clothing. Here's a great article from the BBC about this: https://www.bbc.com/news/magazine-12606943
It could be argued that needing to run the thermostat so high might be indicating extremely poor insulation and/or drafts.
There might also be a case of radiators being too small a capacity for a room so that only the part of the room right next to the radiator receives sufficient heat. (I believe that on average radiators are usually actually too high a capacity for rooms.)