Surprised at local tax bill

This year, although I pay my local taxes throughout the year by direct debit, I have received an additional hefty bill for the taxe d’habitation. This would appear to be for part of the house which was formally a gîte.

I would like to know if other readers have had the same and if anyone has a contact (surveyor or similar) with whom I could discuss the problem.

Gilly Moorfield, Sauveterre-la-Lémance