Serious problem

OK. So I’ve designed a site for a hair salon and I’m now coming up to publishing it, but the problem is that the people who designed their old site ( are no longer in the country and aren’t responding to emails or phone calls. They have the FTP details and the site domain is registered under their name. The service provider says they need written consent from them in order to be able to give me the details. It appears I’m stuck. Any help PLEASE?