196501-503896 FOI Highways

Could you please advise the policy/law/regulation which determines the rules by which RBWM promotes / recommends / advertises the services of "approved" companies to perform services for residents?

As an example, if the council publishes a list of 10 companies which are "approved" by the council to perform services for residents, must the companies be listed in a specific order to avoid giving preference to any of the companies? Such as alphabetical order.

Note that this relates to services which the residents would contact the companies directly to obtain quotes for, and then pay these companies directly. The council is only "recommending" these specific "approved" companies to residents.