Slow fibre speed

[#1]

We had fibre installed ten days ago - the engineer said it may take 10 days to "settle in", which was fair enough.  Today, we were getting between 6 and 11 mbps, which is rather disappointing.  Last night we gave up trying to stream a telly programme because it kept stalling. The highest speed was achieved today from a laptop hardwired to the router by cable.  I'd already tried switching the router on and off.
Can anyone put me right, please?

[#2]

Can you run through the BT Speedtester service at http://speedtest.btwholesale.com
Once the initial result is completed please click Further Diagnostics and run the test there. Let us know the results you get.

[#3]

Thanks for the suggestion - I've just run the test:
Download 12.03 mbps, upload 0.69, Ping 66, and the further diagnostics prompted by BTW said the acceptable range for our line was 8.59-10.74, our IP Profile was 10.74, and that they diagnosed no performance problems.  These results are the best we've obtained since the installation of fibre broadband.
I didn't expect anything like 40mbps, but...this is disappointing.

[#4]

It's hard to say if you have a fault or not. You are within the lower estimates of the line according to the availability checker. It depends on how you are connected etc. Did the engineer give you any guidance as to what he'd expect you to receive?
Tony

[#5]

No, the engineer didn't - we didn't ask.  It's just that we used to get around 4-5 mbps pre-fibre, and so while we might not have expected "Super fast" to mean the 38 mbps at the top end, we quite reasonably  thought it would be a bit more than what we've now got.