The radio head unit in my 2016 Isuzu D-Max LS-T has a list of 10 faults, but the dealer or manufacturer won't do anything to address the issues. I have lodged the issue with Office of Fair Trading and am wondering is there anywhere else you could suggest I could get help with this issue.
You really need to work it out with the dealer and Isuzu. I'd be asking why they don't appear interested in your plight, and press them for some sort of action. Lodging it with the Office of Fair Trading is worth doing, and hopefully that will see some positive response. Beyond that I could suggest a lawyer's letter to the company demanding they take action.