to those on optus, have you tried contacting huawei through the hicare app.
I only did this recently because I had NO updates from my device since I got the device (9.0.0.222) and had always updated manually using otg usb.
I figured this was because it was a replacement phone (original one stopped charging after 2 months) and contacting optus seemed to lead me to a dead end.
however, after contacting huawei support through hicare and giving her the appropriate details. (date of purchase, device serial number, current build) she confirmed that I was on optus and that an update was indeed available (310). So she opened up a case for me and provided a reference number.
at this time I was on optus official 9.1.0.302 which I had manually downloaded and installed. Within the next few days I got the 310 update pushed to my device.
She also asked if I had ever unlocked/rooted... figured I would just be honest and say "yes actually, I figured since I wasn't getting any official updates I would manually update it myself.... but in it's current state, it's bootloader is locked and am on official firmware."
she then gave me a brief spiel cautioning me about the dangers of rooting and mentioned that rooted devices need to be taken to an official service center to be fixed. but if the device is bootloader locked and stock, it should get the update.
nice enough and certainly more helpful than trying to get the update enabled from optus who's response was always "it should be coming soon"