I would get on the phone/email to your ISP and explain that you're having connection problems. They will be able to do a check at their end to see if theirs any problems, you might also have to phone your telephone line provider and see if they can run tests on the line to make sure their are not any faults with the line or at the exchange.
Don't hold your breath though, my BT phone line randomly disconnects all the time for no reason. I contacted my ISP who said I shouldnt have two broadband connections to the one house and that I would need to contact BT. I contacted BT and they said they would run a check on the line but because I was getting disconnected randomly that it might take them a while to find the problem (this is October) still not heard anything back from them despite phoning several times, have read through my ISP's T&C and found I'm not allowed two seperate broadband connections to one house (on seperate phone lines) so I've just had to leave it as it is, some internets better than no internet right?
