I have left a google review of a company stating i found the staff rude and poor service.

A director of the company has threatened to sue me for Malicious Defamation. In order for him not to pursue a claim he has demanded I

a) Remove the review

b) Not to review any of his other companies

c) Pay him £10,000 plus legal expenses.

This was not a solicitors letter and wasn't even on headed paper.

Is he likely to be successful in suing me?