Enforcement Agents - On Street Car Parking Fines

We are procuring for two enforcement agents to take on issuing fines to the public in relation to parking on street, the collection of the fine will be transferred to the LA via the enforcement agent, does the LA need to issue an invoice even though it is a non business transaction?

If the member of public does not pay the fine then another charge will be levied by the enforcement agent and VAT will be charged on this to the LA, is the enforcement agent required to pass these fees to the LA or can they keep them and send the LA a VAT only invoice?  I have read the guidance on Tisonline which says that they cannot net off the fees but I just wanted to make sure.

Thanks in advance