Integration withe Aweber - changing roles

Hi there
We have set up the integration with Aweber and all works fine when a customer purchases a product via Woocommerce.
Everything works fine when a customer cancels a subscription but if we want to downgrade people manually en masse we wish to be able to use the User list and use the Change role function so we can downgrade a whole group of customers from one level to another.
This doesnt seem to work and we have to edit each user individually via their user profile.

Does anyone know how we can do this en masse?
Many thanks in advance
Cheers
Mark