Has anyone had the problem of your Ford 6000 cd radio draining your battery?

I bought a new battery for my Ford Focus Zetec 2006 [because the old one died - or so I thought!], and after getting it fitted I found when the car was stood three days, only one week later, the new battery was flat. When I got the mechanics out they checked out all the electrics and said it was the radio which was draining the battery, which was a common fault with this radio [or so they said]. The problem is it could be expensive to repair. Any idea's guys?