car radio numbers do not turn on or they come on when car is restarted. Please help/advice

I've had my car for about 15 months and I stared having trouble with my radio. The numbers for the radio stations and clock first stared getting all blotchy, and now when i turn on my car or press a button to change a station it either goes off or doesn't turn up. The radio is on and it works I can change the station, but I cannot see what station it is or the time. I bought the car new. And when I last took it to the dealer to get the oil changed i asked to check the radio and described the problem. They said the radio was working fine. It did for a while and now its pretty much doing it all the time. What do I do, go back to the dealer to get the problem fixed or just get a new radio?