Selling property - title not registered properly

[Housesellingstress]

We are selling our house after 21 years. We have a buyer and all seemed ok. We have just found out that the garage that belongs to the property and is part of the sale isn’t registered in our name.
There was a mistake when we bought it and it’s still in the previous owners name as not transferred by the solicitors at the time by mistake. Garage is next to property but joined to a neighbours’ garage and has separate title. We have been back to the solicitors and they are saying we can claim adverse possession for the garage as in use by us for 21 years. The other thing is to contact previous seller and ask to transfer ownership. We could also maybe try and sell the house without the garage.
This is holding things up and very stressful, has anyone else encountered this or has advice?
We are worried about losing our buyers, and the house we are moving to.
Thank you

you don't want adverse possession! if you legally bought it and there is an error then you need Rectification of Title. Did the same firm act? have they got any papers or evidence from when you bought it? you need better legal advice.

It was a long time ago and solicitor is being unhelpful. Though garage being part of sale was clearly part of sale documents. No one has informed the previous seller as didn’t want to give the heads up if could be resolved without them. We don’t know how previous seller will react - they might reappear and try and claim the garage :( The estate agent suggested adverse possession as we’ve been using it for 20 years

You need to pursue this with the original conveyancer. They have insurance for these cock ups. Plus your current conveyancer needs to advise you properly not your estate agent.
Edited to add if they are being unhelpful put in a formal complaint but your current conveyancer should be advising you in detail of your options.