Just doesn't arrive

We had three air-conditioners installed in our office. So far, so good. But one of them is stopped working - whether this is an installation issue or a unit issue (which would be covered under the unit's guarantee), we don't know.<br> <br> We have now called the installer more than 4 times to ask them to come and look at it. They have promised to do so every time we have called. But they just don't arrive! By the time we establish whether this is an installation issue (which should be covered under the installation warranty and Emjay should fix this at their cost) or a unit issue (covered by the manufacturer) the unit will be out of it's guarantee period!<br>