ARW expressed precisely :
What were you expecting the gas costs to be? A serious question, I am not
taking the ****.

I a few years ago out of curiosity - asked how inefficient the usual
gas radiant type room heaters were, compared to running the central
heating. The suggestion was, that they were very inefficient, but no
actual figures given as to just how inefficient. Heating the one room
by that means, versus heating the whole house. Someone had raised the
question before me, in their attempts to save money. I was more
interested in maybe using the heater to supplement the central heating.
The heater had never been used, apart from to check it, since it was
installed.

To answer your question - I was expecting such an heater to be much
more efficient/ less costly to run than it has proven. I expected the
bill to be 1/3rd of the cost of running the central heating. I
appreciate that a lot of the heat produced, goes straight up the flue.