I had a similar experience, a couple of years ago now, was on my honeymoon travelling to a few different destinations, on a particular route (SIN-BOM) we were flying in A330 J in 1A & 1B. J was lightly loaded as well as having a paxing FA in J in row 2.
The service was lacking to say the least, only saw the crew at meal times, tables not cleared for a long time, call bell ignored for a long time, no proactive drinks service, crew chatting in galley whilst pax trying to sleep about their weekends.etc., then the FA was talking with paxing FA behind us for a good 30 mins, whilst we seemed to be an inconvenience when we wanted a drink top-up.
To top it all off when we landed in BOM, got the feared announcement "Mr.cmon0005 please see ground staff for a message", the crew wouldn't tell me what for, as they obviously didn't care. One whole baggage crate was not loaded in SIN and all our luggage was in it!
Then had to queue for 1.5 hours at 2am in the morning, for the outsourced ground handling company to serve us and fill in the report, when asked about cash we were told we get nothing and had to fight for a "lost bag kit" basically a qantas tshirt, toothbrush and deodorant.
Thankfully we phoned ahead to our hotel, and they were fantastic including giving us shirts, extra toiletries, towels, etc.
Anyway long story short emailed QF customer care explaining all this, and basically got an email like the OP's, no acknowledgement that our honeymoon started off on a very bad note, no offer to followup, no service recovery in terms of points or something and they wonder why they had to cut the QF51 SIN-BOM route by treating pax like that.