I've been a member of the Qantas Frequent Flyer Club for a very long time and also, recently, the Qantas Club.
Their Customer Service is appalling. I've written letters of complaint several times and received no answer at all. I expect it now and I suspect that is their game plan. After the initial indignation and writing a second letter and more indignation you realise it ain't going to happen! This makes you less inclined to write a letter in the first place. I'm sure it works for them on this level.
As for losing customers.....Virgin always reply but it's a standard letter with your name and complaint inserted in the blanks and the general tone is 'too bad, better luck next time'. They don't address the complaint at all. I've had no replies from Hawaiian Airlines, United Airlines, you name the company.
At the risk of sounding old - which I am - it happens everywhere now. Once upon a time when you complained people tried to make you happy. Doesn't work that way anymore....probably for a variety of reasons. Nowadays I'm surprised if I do get a reply. I settle for the lessening of stress I receive by writing the letter.