Is your phone service still via the master socket ( so not DV and delivered via the router ) ? , if so , and a neighbour’s broadband (using a different provider ) is also off , suggests it’s probably a problem with the FTTC cabinet, it’s not unusual for FTTC ‘cabinets’ to be wiped out by vehicles crashing into them , or possibly just a failure of something within the cabinet , obviously one type of repair is a major undertaking, the other relatively simple and quick.
As far as being sent a 4G mobile device to give some ‘broadband’ service during the repair time , that is possible but chances are you would need to have spoken to someone who could arrange that , rather than an automated response advising of a MSO ( major service outage ) ….depending on what the issue is , the resolution could be quick or could be not so quick , things like cabinets destroyed by RTC’s usually make local press , or social media for the area .
Unless you have access to a different network, then changing provider on Openreach is unlikely to achieve anything ( as far as this outage is concerned )
