Just had Fibre optic installed but need some info as something seems off

[#1]

So just moved to a new address
The exchange is just up the road and the engineer recently installed the fibre optic line - I should be getting download speeds of 40meg and even up to 80 once its available in the area.
However we are currently only getting download speeds of 400kb sec and websites seem quite slow to load up, certainly nowhere near 40meg line we have.
I did a speed test to compare to other addresses in the area and we were way below them even though we were all on Plusnet.
My question is, would this be something that speeds up over time as it was only up and running 4 days ago but something seems very odd.
Am debating getting the engineer back round.
Cheers

[#2]

Hi,
Thank you for your time on the phone, as I mentioned this should all now be sorted for you. I have created a ticket on your account (#59128491) this has all the details on there for you.
If there's anything else please let me know.
Chris