Land registry

We are in the process of selling our house and the buyers' solicitor is questioning our underbuild as it states on our copia simple that it is space known as a locker (storage). We bought the house in 2016 with 4 bedrooms utility area and bathroom. The paperwork surely must have been in order to be signed off by the notary I would imagine. The land registry had not been updated apparently and we assumed the house was built with the downstairs as being habitable. I wondered who is responsible for doing this change to the registry. We bought the house assuming everything legal was in place.

Very few underbuilds are classed as Habitable by local town halls I am afraid your solicitor did not do a proper job when checking the paperwork.
You need to get these in and see if they can get the paperwork sorted
http://www.martinezdelacasa.com/office/contact.html

Thank you