As for the Customer Service in the lounge, I am curious as to what you think they could do then and there? In this day and age, it is probably best that you complete the feedback electronically, as at least there is record of it.
Bit awkward about flying back the next day with the same crew
I would expect them to pass on the report to the customer service department. All those feedback forms that you fill out online end up forwarding to an email address. This address as well as relevant phone numbers would all be on the internal staff directory. As a premium customer I would expect premium customer service, the desk at the lounge is a "Service Desk" for premium customers.
To be completely honest with you the only way i seem to get a customer service response from Qantas is when i tweet them.
I recently had an issue when I was traveling with a group of people and we had 21 bags checked in, all members in the group were SG or higher. Upon arrival at the location 16 of the 21 bags did not make it, furthermore I had received a phone call from a colleague in a different port who was calling to advise he saw one of my bags (distinguished by a certain type of tag) sitting on his carousel. After spending 45 minutes on the phone to baggage in Sydney as well as dealing with the people on ground at the airport there was no resolutions at all. I then used my phone to tweet Qantas, the tweet then got re-tweeted but a group with a large twitter following and Qantas account got inundated by re-tweets. I recieved a phone call 5 minutes later from customer service advising they were aware of the issue and working fast to resolve it, we spoke about an immediate resolution should the bags not arrive and they actually advised they would pay an ammount of money if the lost bags resulted in me having to buy/hire items (the bags that were lost were mainly pieces equipment for a concert). To cut a long story short the bags arrived 2.5 hours later and all worked out ok.
1 week later I received a phone call from a very high level executive at Qantas om the executive relations department. She said that she had been made aware of the situation and it was completely unacceptable about how it was dealt with on the day etc. She advised that should I ever have any future problems I should deal direct with her office and she also gave me her personal mobile number, she advised I would receive a letter in the mail in the coming days with an offer of compensation for the incident.
3 days later a letter from Qantas landed on my desk with a large bold heading saying "We're Sorry!". It referred to the situation and advised that enclosed was a certificate for a international return space available upgrade from Y to J for myself and a guest to be used at anytime within a 12 month period. It went into detail saying that if I did not receive it on selected flights it would continue to remain valid until the upgrades were successful. There was a ref # and advice to call her office directly when I wanted to use it within 7 days of the specified flights.
Im happy to say that I was successful with using these upgrades, more so I had a single JFK - LAX sector that was overbooked any they could only put me in PE for that leg. The end result of this was Qantas offering me another one way intl business class upgrade.
Note: I have had several minor issues since this incident but I have not contacted her or that department as I don't want to waste there time with small problems.