The switching service doesn’t have any real ‘checks’ ( the regulator demanded no impediments to switching) so things like slamming (an unscrupulous provider signing up as customer that hasn’t implicitly agreed to join that company) or misidentifying an address (basically someone entering your address into an online ordering system or giving the wrong address to a provider, either mistake or maliciously ) can cause these problems , to simply blame BT is likely to be wrong .
The only way to realise something is wrong , is if , seemingly out of the blue , you receive a communication from the existing provider ( email or letter ) saying ‘sorry you are leaving, this is the impact of that decision’ going on to outline the charges that may ensue, if the minimum term hasn’t been completed for example , and also the way to cancel this migration to another provider if it’s an error or the customer has changed their mind .
Did you (or whoever the account is in the name of ) receive any such communication , you need to check in things like the spam folder for emails etc …..it’s very unlikely that BT arbitrarily ceased this account fir no reason , and almost certainly were told by the switching service that a new provider was ‘taking over’ your service, the systems in place that allow this type of thing to happen are because Ofcom place the switching providers requirement for no barriers ahead of the customers potentially being slammed , there used to be a two stage switch , there is now a one stage ( one touch ) switching setup , and isn’t BT’s ‘design’, and can hardly be held responsible for its failings
