Closing Faults Without Resolving Issue

I've been logging faults since December because my ADSL connection has been constantly disconnecting. Every time I log a fault, the fault is closed without the issue being resolved. The whole process is flawed. Technicians don't phone before they come. They just pitch without confirming whether you are available. There is no way to get hold of the technician when the problem is being experienced. If the problem is not manifesting itself while they are there, the fault is closed. If they witness the issue, they leave and the fault is closed without the issue being resolved. Escalating the fault has not helped resolve the issue.