By 'alignment' do you mean a bornage? And what is the 'declaration' that you refer to, a week between getting the paperwork organised and the construction done does seem a bit of a short time scale. Is the Maire saying that it's the type of fence that does not comply, the height, the construction, all of which may be seperate issues?
I can send you the details of the legalities of hedging (send me a pm so I have your email address) and fencing is dealt with the same way tho there are local regulations which may apple for style and type. Are you in a conservation, restricted area, that may influence things?
Sorry to say this but regardless of you owning the land, there are regulations that impact on the placement and height of these things, they're national laws, not open to local interpretation and you have to comply, it's a community thing, not necessarily a personal thing - and if others don't comply, it doesn't mean that they think you have to.
I'd be speaking to the Maire asking for further clarification, visit to your place etc and get his/her response in writing.
If you followed the procedures and applied for permission in the proper manner they cannot change the goalposts after permission has been granted.As long as you have erected exactly the type and size of fence that you declared in your planning application then the mayor has no right to tell you to take it down.
On the other hand if you erected the fence without making an application first.......
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