In England and Wales it is not possible for a third party to appeal against a local planning authority's decision.
For example, if your neighbour was granted permission to build an extension you could not appeal against it - even if you objected to the application at an earlier stage of the process.
Your only recourse in these circumstances are:
‘Calling in’
Asking for the planning application to be ‘called in’ by the Government. This only happens on major applications. See the relevant pages on the Planning Inspectorate web site for details.
Judicial Review
A judicial review of the planning decision: again a serious and potentially costly business. A helpful guide to judicial reviews in planning has been provided by the Campaign for the Protection of Rural England.
Complaint to the Ombudsman
In some cases, complaints about how a local planning authority handled a planning application can be referred to the Local Government Ombudsman.
The Ombudsman has no power to alter the decision, even if the planning authority are found guilty of maladministration.
However, in cases where the Ombudsman adjudicates that the local authority has acted incorrectly in handling a planning matter, the Ombudsman can order the authority to pay damages to the complainants.
Talk to the developer
If you are unhappy over a matter of detail on a major application it still might be worth trying to persuade the developer to your point of view. On major applications there are often requests for variations or revised applications submitted and the change you want might be included if you can get the developer to agree.