If some of the rooms in your home feel like they are boiling hot when the heating is on and at the same time some of the rooms feel as though they aren't being heated at all, you have what's known as an "unbalanced" central heating system. Essentially the heat that is being produced by your central heating isn't being distributed evenly.
This is actually a very common problem since rarely do building contractors actually properly set up the heating system before they finish the job, meaning it's often left to you to sort out instead. However, it is a problem that has a solution (you probably just breathed a huge sigh of relief!). You need to have your system "balanced," which, if done correctly, should solve the problem and further alterations shouldn't need doing unless serious changes are made to your home heating system.