Help! Potential soil stack issue

I live in a block of flats and the flat above me is having an issue in their on suite bathroom with heat potentially rising up through the soil stack which is causing water damage to their flat and their mains drainage pipes are extremely hot to the point of venting steam. I do not have this issue, neither does the flat directly below me (same layout), however at present the toilet in my on suite is out of use due to a broken cistern, so I am using a different toilet on the other side of the flat. Before I go paying out for a plumber to resolve something that might not be my issue, does anyone have any idea on what would be causing this? Thanks in advance.