This might be helpful or confusing but I'd like to share.
I just got off the phone with a level 2 Immigration officer, she asked me personal information to prove that I'm the petitioner, she asked me the date I made the payment, she re-confirmed my mailing address and full names. She finally was able to pull up my IOE receipt number which I wrote down in paper.
She advised me to track my GC card status online next time at my convenience. She checked my GC status and she found out its still in process. I think that's quite helpful and a huge relief. Another point she said was it would take between 30 to 90days (depending on nationality) for a first time GC applicant to have the card mailed out.
Best I'd advice for anyone in similar situation is to call the immigration number and politely request for a level 2 officer's assistance, they would try to convince you, but please politely insist on speaking with a level 2 officer. It works for me and did saved me all the generic verbatim info the level 1 officers give you.