You would be wise to consult a specialist planning legal advisor/lawyer, not anyone else, as this relates to legal issues and precedent not normal planning advice. You may have legal assistance on your home insurance policy.
Whether the conservatory could (or should) actually be enforced against, and whether the alteration is a material change of use or a repair is one thing that could be debated.
Generally, there can be no reliance on any council officer's opinion or advice. All that matters under planning law are decisions that come from a formal application or action.
There could be appeals to the Planning Inspectorate following any formal enforcement action, but some types of action - eg contraventions or pre-enforcement warnings can't be appealed.
There may be options to complain of maladministration to the council under their complaints process and then to the Local Government Ombudsman. This cannot reverse a planning decision, but will deal with the process and whether the council was wrong or right in how it dealt with things, and how this impacted you and maybe costs incurred
Whether the conservatory could (or should) actually be enforced against, and whether the alteration is a material change of use or a repair is one thing that could be debated.
Generally, there can be no reliance on any council officer's opinion or advice. All that matters under planning law are decisions that come from a formal application or action.
There could be appeals to the Planning Inspectorate following any formal enforcement action, but some types of action - eg contraventions or pre-enforcement warnings can't be appealed.
There may be options to complain of maladministration to the council under their complaints process and then to the Local Government Ombudsman. This cannot reverse a planning decision, but will deal with the process and whether the council was wrong or right in how it dealt with things, and how this impacted you and maybe costs incurred
