I believe HCI is no more as the Government has stopped funding it so getting redress from HCI will be rather difficult.
The main part contract was to supply you with a computer which is what Elonex did so they have fulfilled their part of the contract and there is no breach.
The service agreement was with Elonex (I presume) and as they seem to have gone into liquidation there is no one that you can sue or pass the blame to. There may be some help available that other forum members could point you to but in the absence of anyone to contact you are not in a good place.
...howeevr if you explain the faults on this forum you may be able to get a lot of excellent help for free. Use a separate thread for it.