On the form it just says 7 days, not clear or working

II paid £110 to a county court to cover a court hearing. I settled my claim amicably with the defendants and then requested their return of my £110. I then received a letter from the court stating it would not be returned because I had not given 7 clear days notice. The letter asking for the refund was received by the court on the 16h and the hearing was to be the 24th. 17th to 23rd is 7 clear days but they have failed to return the hearing fee!

Can I sue the County Court for money wrongly withheld