Landline number portability is moving a number between providers while remaining in the same property , moving house is something else......although it’s being wise after the event, if the idea was to keep the number and use Virgin ( not Sky ) at the new address and assuming that their physical network would allow this it, the process that may have worked would have been to use number portability to switch from Sky to Virgin at the old property and then use VM’s home mover service , assuming they offer such a service , to take the now ported to VM number ( that was previously BT and Sky ) with you to the new address, attempting to do both things on the same day with one ‘order’ was always likely to fail.
As already indicated , if the number has been returned to BT , the only realistic way to eventually get the number back would be to join BT at the new address , again assuming both addresses are from the same ( BT ) local exchange, as far as any comeback on Sky or VM , you won’t have any claim, you may possibly get VM to release you from any minimum term at the new address , but even that would be a good will gesture, that they may not offer.
