Do you know if he is still trading?
Is he running a limited company?
Proceeding on the basis that this is a fault caused by his work then he is clearly liable to put it right or compensate you so that another can do so.
Whether or not it is caused by his work is another matter. It seems likely in all the circumstances. I’m not sure how he could deny it.
He may not be keen upon taking remedial action but that doesn’t mean you don’t have a valid claim against him.
Obviously limited companies are easy enough to close down so that is a risk but if he has been trading for some time that is unlikely.
You do have to give him sound notice though before you instruct another and sue him for the cost.
Can I clarify anything for you?
Do you know what the cost of putting it right is?
It is not really worth getting a solicitor to do it then. A solicitor will charge about £100 plus VAt and you cannot claim it back.
A barrister under public access might be cheaper but you can send a letter before action yourself for free.
It will be about £100 to sue him. You can do it here
But I would give him 28 days warning.
Yes, but give him a specific date - unless he responds by 4pm on X date you will take these actions.
then there can be no argument.