Internet Service Providers

[Dudley]

I'm with one of the lesser know ISPs and for about 8 years I had no trouble until recently when I lose my Internet connection on a regular basis. It all seems to stem from when I opted for a lower tarrif and cut down from 60gb of downloads per month to 30gb (which should be plenty as I usually use less than 10gb per month). The ISP says everything is fine at their end and it has nothing to do with the tarrif but it seems too much of a coincidence. I recently tried a new router which worked faultlessly for three weeks before I got the same problems again. Through the ISP I have had the BT line checked several times including PSTN (voice channel?) with no faults found. With the new router we changed the little ADSL box and we have two very new laptops in the house both running Windows7 (although the faults were there when I had Vista), so I can't think what is causing the problem. Does anyone have any ideas please? I realIy respect you AB techie guys who have been very helpful in the past. I am inclined to change ISP and go for O2 (who seem to come out best in all the tests) or even BT who offer the facility to send an engineer to set things up. Any advice gratefully received.