I had a similar issue with CZ flights crediting last year; I got the same form email you did at one point in the exchange. (In my case, the fight was over CAN-CDG/AMS-CAN flights, so a far less trivial 4600 miles, and I was determined to get the minimal bit I was owed for my SYD-Europe round trip!) Flights didn't post automatically at all. I emailed the boarding pass and eticket in, and Delta credited the flights as S (0% miles) instead of the M (40% miles) I booked. The following (far more polite than yours, despite how I felt at the time!) email did the trick in the end. It was my third email to them on this particular claim. Ugh.
Dear Mr XXXX,
Please reread my email. I am not asking for credit in an excluded
class of service. I am asking for credit in class M on China Southern,
which is the class I booked, paid for, and flew on flights CZ308 and
CZ783, as indicated in the booking confirmation I attached to my last
email. According to your web site, this booking class earns 40% miles.
Cheers,
ashill
Dear Mr YYYY,
Thank you for your prompt reply. Flights CZ308 and CZ783 have still
not credited correctly. They were each booked in class M, not class S.
Class M flights on CZ should earn 40% miles according to your web
site. [irrelevant sentence snipped]
Cheers,
ashill
Now, Delta has apparently stopped replying to my emails at all in regards to more recent flights which have not credited. Lovely.