>> because the download speeds did not go any faster than 2.5mbps
I still suspect the problem isn't to do with the physical line - the conflict between the speed on the BTw performance tester to that elsewhere points to the ISP side of things.
>> BUT we had some power issues last night and the modem resynced 3 times in an hour.
Damn - that wont help :/
>> He did mention that my Noise Margin was alittle low and got that changed slightly.
Puzzled on that remark - your SNRM was perfectly fine on the stats that you provided.
May be worthwhile grabbing a copy of
routerstats and setting it up to monitor your SNRM over the course of a day.
Can you also do another BT performance test to see what results that gives you and also your IPprofile please.