Changing providers with Digital Voice

iniltous

You paid who exactly for a ‘better’ router ?, if you bought a yourself a non BT router then it wouldn’t support DV ( digital voice ) and obviously you are not required to send that back  , if you were migrated to DV ,BT supply a SH2 to those that didn’t already have a BT supplied one ( as a SH2  is necessary for DV ) , if BT supplied you with equipment after a certain date it’s loaned and should be returned when BT no longer supply service …..if you bought yourself a SH2 before you were switched to DV , you should have been supplied with a second SH2 , or could have requested one if one wasn’t automatically supplied.
Your new provider Sky also require equipment to be returned if you cancel service with them.