Welcome and thanks for posting. I'm really sorry to hear you've been having trouble with intermittent dial tone.
I'm having some trouble locating your account to run some checks. Do you still have the engineer booked? If you do I would leave the engineer attend to take a look at this for you as its been on and off up to this point. If you'd like me to take a further look at this for you I will need some details so we may have to take the conversation private.