As suspected, Openreach cannot deal with this type of request via the number suggested, nor any phone number. After speaking with several different people / departments, the route for requesting this be dealt with is:
Send an email to network.rearrangement@openreach.co.uk with the subject "Urgent rearrangement of cables". Include your address, contact details and a description of the issue with a What3Words location for the cable. There may be charges associated with this work which you may be liable for, depending on the situation.
It was probably marked solved as this type of query is out of the scope of this forum. This type of work would need to be actioned by Openreach and not BT consumer.