Solved! Go to Solution.
Presumably the problem was the equipment used at the telephone exchange. When you moved to Sky you moved to their equipment. With Infinity you would be on completely new equipment for your broadband. I don't know enough about telephone exchanges to know what would happen to your voice calls but I would imagine it isn't likely you would end up with the same line card. I could be wrong. I doubt that there are any checks that could be done.
It sounds like you had either faulty exchange equipment (as mentioned) or a faulty copper line that was swapped with the change over to sky.
I wouldn't think they'd put you back on the same equipment as before, and if they did you would be able to raise a fault on it.