Can’t update testemonials heading

Hi There, I seem unable to update the testemonial title from 'People who booked us say...'. I'm using the latest version of the theme. I can update the other titles fine, it's just this one.   See: https://www.dropbox.com/s/e63xnhlwoeaj4ze/Untitled.png?dl=0. Website is www.feloniousfunk.co.uk.   Thanks!