I forgot to blog this, it actually happened last month.
After several lengthy cutouts my broadband connection finally went down altogether. The modem diagnostics program said I was 'desynchronized'. So I phoned the Orange call centre, and after the usual long list of irrelevant questions we came to 'do test'.
"The test says your connection is desynchonised'.
[Yes, that's what I said half an hour ago]
"I am going to ask BT to do an intrusive check. Please leave your modem plugged in and switched on but do not try to connect for four hours".
This worked fine, evidently the BT Engineer located the fault. Orange even phoned me the next day to make sure I was indeed synchronised again.
Call centres do work, you just need the patience of a saint.
Where does that expression come from? Saints were often irritating, impatient and eccentric people who annoyed the regular clergy no end.