Thanks for reaching out to us loyalcust, and welcome back to our Community Forums!
Sorry to hear of the desire to port the landline phone number away from Virgin Media.
We would have to advise that if you're within a minimum term contract, for this service, the porting would be deemed as a form of cancellation and therefore early disconnection fees would be applicable.
As for the discount being removed, this isn't something I can advise from this vantage point, but do please come back to me if you are keen to understand further the potential implications of the porting out of the landline number
Thanks,
David_Bn