It's interesting how experiences stick with you – many years ago I was with a company called Demon Internet and for some reason it was paid through my credit card. Credit cards expire, it's a fact, so anyway, I inadvertently stopped paying.
Now, I'll admit my fault, but really some kind of notification would have been fine, or a call, or anything other than cut off my internet right there and then and tell me what I owed them had been passed along to a collection agency. Au revoir, dear long-term customer!
Same with EDF, with whom I engaged in a never ending battle to stop them sending a bill literally to 'the meter on the wall adj number 51.' They couldn't, for reasons impenetrable, give me online access (despite me being the company secretary of the business) and because the postie would simply leave bills by the wall, they would blow away. They would agree that yes, it was totally out of order, and singularly fail to solve what would seem an elementary problem of an address change. Just to taunt me, they did briefly manage it, and then reverted it for the next bill. I don't think it was ever solved.
As for droppy wifi, I had issue with a wilting radio signal for years, partly solved with an extender, but I did buy mesh system (TP-Link Deco M5) and it's been fantastic. Someone with better knowledge of Virgin modems will have to explain to precise details (I'm on BT), but it set-up was a pretty straighforward five-minute job.