Unable to provide item purchased

Hi I bought a tv from House n home Newcastle on the 24th of November I was promised to receive the tv by the 1st of December Now they same they cannot get stock of the tv No apologies or communication from their side. I bought a Samsung 55 Inch ultra hd tv They have a LG with the exact same specs which they do not want to give me. They want to give me a tv with less features and lower picture quality which is similar to what I already have. I want what I paid for or something equivalent to my purchase. Are they allowed to do this?