Improving Bluetooth headset radio reception

I currently have an Interphone F5MC Bluetooth headset which I primarily use for FM radio listening while on my 1 hour motorway commute. I previously used a Sena 5. Both my current and previous systems struggled to receive signals very well despite not being far from a big city. In fact the motorway I ride is the M25 which is effectively London’s ring road. The signal should be fine and is in my car. These headsets use the speaker cable to the further headphone as the reception antenna but despite all my efforts to improve the routing within the helmet I cannot improve reception. Is there any other known way to improve matters?

I don't know much about your current headsets. Most are more for communication not great at other things.

I used to have a Sangean pocket radio, very good FM reception. DT-400w Fell off mount never seen again.
Worked very well. You could BT it to intercom with some kind of adapter. Has a standard headphone jack. Make sure BT will connect to headphone. Some cheap ones have issues.

Radio is about $65-75 US. Adapter who knows. Radio runs on AA batteries but lasts for months.