Lg Prada and Voyager 855 headset

Recently purchased the Voyager 855 Bluetooth headset, and I tried to use it with my Prada LG cell phone. The phone calls were no problem, for I could hear them very good and clear, even in stereo mode. Yet the problem came when I tried to listen to stereo music from the MP3 player of the cell phone. The music jumps very strange, and after a few seconds of strange playing, the headset disconnect from the phone. I have to turn off the MP3 player, so the headset returns and connects to the phone. I have checked the Bluetooth specifications of my cell phone, and apparently its support the A2DP technology that it is needed to hear the stereo feature. I contact the Palantronics tech support department and told me the following: “Check that the phone is set to the Bluetooth mode of the audio application(stereo or mono). The headset will connect to either a hands free/headset(mono) or A2DP(stereo) Bluetooth profile. If problem continues, reset phone and repeat the pairing of the headset to the phone”
I thought of the solution at the first place, yet I didn’t find any options on the phone to change the configuration from stereo to mono. I checked the Bluetooth options and the general settings options without any success. Can anyone help me please? I really like the headset and it will be a shame to return it.