Fax problems after broadband installed

Three_Jays_2

After horrendous problems with Virgin Bb for over a year I signed up with BT Total Broadband. That was on July 9th, and Bb has been fine ever since. However, for the last week or so it has been impossible to send faxes except on odd occasions. The fax is a computer program, using the landline. Usually it says there is no dial tone, and there is a lot of noise on the line, even on voice calls. My telephone provider is Tesco Home Phone and they tested the line and said there had been a fault, which had been rectified. For a short time I was able to send faxes again, but then the same problem recurred. Now I can't send any at all. There are ADSL filters installed and a router for Bb. Please can anyone help?