every time i try to connect my mobile to the the cars bluetoothi get a bonding failed message on the stereo...can anyone help?

 

What phone is it?

 

sony erricson w705,,does the stereo only accept a certain amount of fones bonded to it as i have went thru a few mobiles since owning the car and now if i try any mobiles to connect i get the same message,can i clear the stereo or bluetooth?