How long until the line 'settles'?

[#1]

New customer since Wednesday. On that day the speeds were fine. Since then it's become erratic, and right now it's unacceptable. How long will I have to put with the speed you can see in the attached image?

[#2]

Have you tried restarting the router? (Best to do that in daylight hours.)

[#3]

The advice given in the 'Welcome To Plusnet: Getting Started With Your Wireless Router' booklet says I shouldn't switch the router off because the exchange will think my line is unstable and reduce my speed.

[#4]

Hi Havel, the speeds you posted are totally & utterly unacceptable.
I've been a Plusnet customer since mid May & my speeds settled down within a couple of days.
I never had below 9Mbps, not even on first connection.
Go into the 'Help & Support' section, scroll down to Help Assistant & then click on 'Ask a Question'.
Here you can attached a copy of your speedtest findings.

[#5]

Hi Havel,
Sorry to see that the speeds aren't up to scratch yet. I've just performed a number of different checks against your connection but no obvious issues were highlighted.
I'd advise heading to http://faults.plus.net to take that further.
Adam