The bike is pretty clean, and that's good. Did you buy it (2015) new? If so I'd be talking to the bike shop.
I'm not sure what they make those bars from - from a cost perspective I would imagine they are mild steel. Mine are OEM, not the same as yours but similar. Mine are not stainless nor aluminium (test with a magnet if you like).
If they are mild steel, you could get it welded. There is a very small chance they are tempered, and that would make welding a problem. As long as the metal is not a difficult temper and in good shape, a weld can be a sound solution.
The location of the break might indicate that the fit isn't great, and there's been considerable stress at the 'T' joint there, so check on fit before you reassemble.