Poor speed with Plusnet Fibre

[#1]

Hi, since being on fiber connection I have been getting anything from 11mb to 28mb download speeds of an estimated 80mb that I was quoted. I have also experienced connection drop outs, I was better off with ADSL compared to what I'm getting now, at least I had a more stable connection of 16mb.
I have tested the speed on a wired only connection and I've also connected with a PPPoE connection to rule out anything my side of the OpenReach box and it makes no difference to the speed, pointing the problem directly to BT's end of business. Is there anything that can be done that won't involve me paying for a BT engineer to come out to investigate a problem with their lines or exchange?
I've done a test using http://speedtest.btwholesale.com/

1. Best Effort Test:  -provides background information.
Download Speed
18.42 Mbps

0 Mbps 77.44 Mbps
Max Achievable Speed
Download speedachieved during the test was - 18.42 Mbps
For your connection, the acceptable range of speedsis 16 Mbps-77.44 Mbps .
Additional Information:
IP Profile for your line is - 77.44 Mbps
2. Upstream Test:  -provides background information.
Upload Speed
4.01 Mbps

0 Mbps 20 Mbps
Max Achievable Speed
Upload speed achieved during the test was - 4.01Mbps
Additional Information:
Upstream Rate IP profile on your line is - 20 Mbps

[#2]

Can I get any help please?

[#3]

Hi there,
I've checked over your connection and can see no obvious cause for the speeds you're seeing.
I'd suggest running through our faults wizard at http://faults.plus.net
The diagnostic test that you go through on the faults wizard will help rule anything internal out causing the issue and help rule out any engineer charge if an engineer visit was to be required.

[#4]

Thanks Chris