Huge difference in speed test results

[#1]

How is it that when I use the BT Wholesale Broadband Performance Test for download speed I consistently get a reading of 17Mbps, yet when I use the My Broadband Speed Test (via Connection Settings on PlusNet) for download speed I consistently get a reading of 2Mbps?
I am aware that the latter is preceded by the warning ‘We are currently experiencing issues with our speed tester and results may not be 100% accurate’, but this warning has been displayed for months and the regular huge discrepancy in the two readings is so large that the caveat seems irrelevant. Can anyone throw light on this please?

[#2]

Hi,
The 'My Broadband Speed Test' isn't at all accurate which is why you'll get a discrepancy. If there are a high number of people using this speed tester at once, you'l not see results which are consistent with the BT Speedtester.
I'd recommend using http://speedtest.btwholesale.com/ in the meantime whilst we get the speed tester fixed.