Here's an update from my side, we applied on the 02 July 18. On the 03/01/20, I sent a complaint to the department saying that I crossed the 18 months period specified on the website.
Got the standard reply saying that the email has been transferred to the appropriate department. on the 07/01/20, got a reply from CO Dat, saying that the evidence I submitted as requested by CO Sophorn on 23/05/19 is not valid. It took them 9 months to give me this feedback. I'm sure that my complaint triggered them to check my file but to get this as an answer is plain pathetic. I gave them exactly what they requested and now they are saying that it is not valid and gave me another 28 days to submit an EILTS result or another proof of functional english for the secondary applicant. I'm spewing!!!
I guess the take away for everyone here is that if you are past 18 months, file a complaint straight away to force them to open your file, before the time increases again. However, they might come up with some other crazy stuff for you to do.