Bluetooth device interference

I find using my Tomtom Live services that the bluetooth link between phone and Tomtom interferes with the bluetooth link with the hands free kit. It cuts the phone off mid conversation. Works for a bit then cuts off the car kit. (I presume the Tomtom polls the phone periodically.)
Has anyone found a way round this?
I can't find any way temporarily to turn off the Live Services link either. Only turning off bluetooth hotspot (fiddly and impossibly whilst driving) on the phone or rebooting the Tomtom will do it. I can't find a way temporarily just to disable Live services on the Tomtom.
This whole situation basically means I can't use Live services as I regularly get phone calls on the hands free.
I have now deleted the phone in the services set up after 3 days of trial use which got rid of the problem and of Live services. Annoying to have to do that.

Comments
The Tom-tom comes through the car speakers and has a proper noise cancelling mike. No comparison.
There should be an on/off toggle for Services. It's ridiculous.
Workaround is to delete the phone from the services setup and then reinstall it anew each time I want to use it. I'm getting quite adept at it but not a good solution.
Anyways, nobody has an answer to this? It's a permanent "feature"?