This isn't too easy a question to answer! I'm not sure what is meant by a "formal question". If you make a request under the Freedom of Information Act, there are procedures to be followed. But otherwise I'm not aware of a general legal obligation on a town council to answer questions by members of the public, formal or not.
It sounds as if what you really want is enforcement of the section 106 agreement. I may be mistaken, but my impression is that this would be a matter for the planning authority, which would typically be a district council. The town council could urge the planning authority to act, but I would doubt whether it has a power to force action.
It is probably worthwhile for you to ask for clarification from your local plannning authority.