Just in case you didn't know...

Holidayextras have a "Free If" price guarantee which refunds the room if you could have booked it cheaper within 24 hours of booking with them.

A bit of googling (before you book with them) can 'occasionally' find the Sofitel & Parking cheaper than holidayextras hence you get it free. I usually find IHG hotels are easy to find cheaper and sometimes Hilton.

There are strict conditions which they apply stringently especially the cancellation conditions which have to be identical - HE are 24 hours, many sites are c.72 hours.