Whining Noise from WRX Rear End
 

Got a very odd problem with my 55 plate wrx.

When slowing down in 4th or 5th I hear a whining noise coming from the rear of the car. Odd thing is it starts at 65mph and stops at 60mph then nothing. If I accelerate back up it does it again but only in that speed range.

Only had the car a week and a half and have now taken it back to the garage. Problem is I think they are going to say it is a normal noise and nothing to worry about. That maybe but it's really annoying and nags at me every time I drive the car.

Car has only 33K on the clock and a full Subaru service history.

Does it sound like a normal noise to be happening?

Many thanks.