We've lost at least one here too, Collins in Sth. Melbourne, I don't know I recon. they've probably been around 20 yrs too.
I found out when I rang them and no answer, rang out 3 times, so I rang Mitsu HQ, they told me. I expect they could have organised Collins to put a recorded voice announcement on the number. I guess it didn't end in very good terms, I hope the techs and parts guys are multiskilled.