Denon UD-M30 (CD Receiver) bought U.K. using in...

Question

Massive sudden increase in volume 15 to 30! Can this be a remote device being used by a neighbour? Can't think of anything else! Using a "surge protector" bought in Fuerteventura, but don't know what else to do. Can't ask neighbours to stop using their own devices, and anyway Spanish is not good enough to explain problem. Has anyone else had similiar problems?Will be devastated if we can't play our music!
Hope somebody out there can help!
Regards from music lovers [e-mail]