Back in September 2018, I downgraded from Fibre Extra to Fibre.
When on Fibre Extra my speeds were around 44M download, 12M upload.
I was on Fibre Extra because I needed the upload speed (normal Fibre was a 40/1 or 40/2 service).
When the normal fibre product changed to 40/10 last year, I downgraded to save a bit of money.
Once the downgrade was done, my speeds changed to 39M download 9M upload (as expected).
Since Jan this year, my download speed has been 19M (upload still 9M).
Has the Fibre product changed from 40/10 to 20/10?
Fixed! Go to the fix.
I'm sorry to hear you're having issues with your speeds.
We've not made any changes to our Unlimited Fibre package since moving it from 40/2 to 40/10.
I've identified the problem with your speeds. It looks like the speed profile on your account for some reason has reset itself to the max that standard broadband can go at 21mbps.
I've fixed that now, could you reboot your router letting us know how your speeds look afterwards?