Hifi corporation are not ethical

I purchase items onlin on the 25 of November at hifi corporation while it was showing it's available, even is the 17 of december is not yet delivered ,when I call then they don't answer their phones until I start chatting to the guy buy the name of Chelsea on their website and he said he log a complain but after that they are telling me that they are out of stock even it they promised to deliver the Items within 10 days,and they don't even communicate with me unless I try to communicate with them but always I don't get the satisfied answer from them.