Credit score massively downgraded

I recently attempted to get a (duplicate) Virgin Media Broadband package in my home and Virgin performed a hard credit search. 

This duplicate account has now been cancelled - there was no installation and no money changed hands. 

However the hard credit search remains in place and has made a large decrease in my credit score. 

How do I go about getting this search removed?

It doesn’t seem fair that:

a) it was not clearly pointed out that a mere £28/month subscription would result in a hard search 

and 

b) the search needs to remain in place if I no longer require Virgin broadband. 

Any help appreciated. Thanks