I would check your flue is high enough to take away the smoke - it may not clear the ridge line of the roof of your house- hence the black soot line. Mine does this and my dads used to do this too until he went to the guys who he bought the wood heater from and told them bout the problem. they recommended another length of flue - which eliminated problem and so you would only need to clean and repaint wall - and get the company back to ensure enough drawing of the fireplace is happening to eliminate the smoking issue. also check you are not burning too much green wood as burning wood that is not dry enough can cause this problem as well and will save you buying a piece of wood and ruining the modern look that you wanted. - just my thoughts.

Great looking fireplace you have there! I agree it looks Art Deco and placed in the corner of the room, it makes me think your house is older than 50yrs. I'd guess it was built more like in the 1930 -40's. The gas heater and tiles looks like they were installed around the 60's. And the original tiles were ripped up and replaced with the ones you see. The rubble-y area on the side was I believe the original hearth. The new tiles didn't quite line up with the old. And no doubt, modern new wall to wall carpet was installed over it the same time so they didn't worry about it. If it was mine, I'd get a plumber in to disconnect the gas and pull out the heater. I'd then see if the chimney was in working order. Do you have chimneys on the roof you can see? Then replace the tiles and paint the surround. There's a good chance there is a void behind the gas heater. I'd look into making it back to a working fireplace. If not, I'd pop some nicely cut decorative looking logs into the space. You could remove it but it's lovely and the room looks large enough to put a wardrobe over the opposite wall to the bed. Lastly could be a bit of work to remove the wall as I'd expect it is masonry and need to check that it can be taken out without structural damage to the rest of the building. Often these fireplaces were paired up with one in the room behind. Do you have a corner fireplace in the next room?

haha!!!! Siri - you can have your Eiffel tower angel... give me the beach any day :) Nic - perhaps some driftwood, shells and a jar of sand might help bring the beach to you - just don't knock your sand flying or you'll literally be able to crank up your fireplace and lie down on your sand to sunbake lol.

Keeping it all the one wall colour is more modern as per the pics. My earlier comment was more traditional. Either mantle or mirror or pic frame above could echo kitchen. White corbels. But rather than wall colour for mantle, if you aren’t going black, I’d match the architraves to help it pop just a little. This would be my preference.