are you able to share here what kind of explanation did you provide them. Would benefit a lot of users here. ThanksGuys, if your card processing is taking way beyond time and have plans to travel, my suggestion is to send a solemn declaration via mail to Case Processing Centre in Sydney. Yes, the website mentions it is only applicable for those whose cards have been sent but not received. But I still sent them anyway through Xpresspost with a letter of explanation and itinerary (if applicable). They received it on the 6th, got my PR Card approved on the 7th and received my card yesterday.
Also, emailing firstname.lastname@example.org helped in terms of speeding up.