Luce
I depends on how the broker is operating. Some just broke policies and have limited ability to negotiate premiums with the Insurers. Others are either owned by Insurers or have purchased underwriting capacity from Insurers. For example a number of policies offered by Swinton are with their parent company MMA. Some Brokers have their own Insurance schemes, having purchased underwriting capacity form Insurers at wholesale rates and have some room for maneuver.
As for mollies original post, I stand by my comments. Her Insurers will charge short-term rates when policy is cancelled mid-term and she will have to decide whether it is still cheaper to arrange Insurance elsewhere, after paying this.
My comments stand that irrespective of how the Insurance was arranged, there is nothing to stop mollie challenging the broker/insurers about the competitiveness of the mid-term adjustment quote. They cannot stop mollie getting a new business quote with the same Insurer and making a comparison to go back with.
Whilst I take your point about the fact that following the change of car the Insurers may no longer be the most competitive, due to the cancellation/short term rates applied, this makes this difficult for mollie. I cannot see any harm in obtaining the new business quote with the current Insurer to see if they are overcharging for the mid-term change. If the following this quote, it just shows that they are expensive for the new car, then obviously mollie will just have to make a choice. I would expect her broker to provide a service if they wish to keep her as a customer.
Finally there is no reason to be rude when posting. If you have a different point, just make it.
Huckster