This would appear to be the official website for Sunny Beach. Perhaps an email to them might elicit an address.

http://www.sunny-beach.com/

fwh

I came upon this on another website where someone was looking for a police station in 2008 to report a theft and he wrote to:-

Slanchev Briag Police Dept.
8240, Opposite Kuban Hotel
Sunny Beach
Burgas

Tel. 00359 249 32559

But he never returned to say if he'd had any success ...

And you might consider contacting the Bulgarian embassy in the UK at

http://www.bulgarianembassy-london.org/index.php?option=com_contact&Itemid=243

which includes a form on which you can write a message and contact them .... good luck, and hope you resolve the problem.