Scottish Power still provide the backhaul connection and support the switchgear installation, you will find that the installation was completed by a private contractor (GTC are getting big in this area) and they manage the "last mile" connection, the LV connectivity to the home. The HV lines will still be managed by Scottish Power (or whoever the local incumbent power supplier is).
I feel your pain Igni, deploying on New Build is not as simple as everyone thinks it is