Bluetooth Handsfree Hassles

Have now got Motorola HF850 Fitted to my car - now realise made the wrong mistake by going to Halfords to get something fitted - now on my 9th visit to them to get a suitable solution, have tried Halfords own and Parrot but was very poor call quality with both. Now on the Motorola HF850, call quality is good, interface is good but even with the external speaker cranked up to max any speed over 40mph is drowned out with tyre noise. Does anyone know whether it is possible to increase volume further as I don't want to go back to Halford's again as every time the car comes back there is another scratch or three on the dash area. Many thanks