Week old fibre upgrade has slow download speeds

[#1]

Hi,
Last Wednesday the Openreach came and upgraded our broadband to fibre (up to 40mbps). While he was there I tested (wifi on phone using speednet) 36.+ downstream, 11 odd upstream, very happy.
That and the next day we had very fast speeds, tested next day, similar speeds, all good.
However since then it's been back to the same download speeds as before we upgraded, ie about 2mb or up to 3 on occasion.. Upload is way faster (8-10mbps) but that's not very useful or important for our usage.

Results of BTW performance test:
1. Best Effort Test:  -provides background information.
Download Speed
2.35 Mbps

0 Mbps 38.71 Mbps
Max Achievable Speed
Download speedachieved during the test was - 2.35 Mbps
For your connection, the acceptable range of speedsis 12 Mbps-38.71 Mbps .
Additional Information:
IP Profile for your line is - 38.71 Mbps
2. Upstream Test:  -provides background information.
Upload Speed
7.57 Mbps

0 Mbps 10 Mbps
Max Achievable Speed
Upload speed achieved during the test was - 7.57Mbps
Additional Information:
Upstream Rate IP profile on your line is - 10 Mbps

Any ideas please? Usage is just normal web browsing etc, streaming video (when lucky enough not to get constant buffering), no peer to peer/torrents etc.
Thanks

[#2]

Hi there,
It looks like the speed profile just needed to be updated as it had for some reason reverted back to the same one prior to the fibre install.
Let us know how things go.
Adam

[#3]

Thanks Adam,
Checked last night, situation unchanged, then rebooted the router today and hey, downstream speed is a very reasonable 17mbps.
cheers mate!
Niamh