experiences with kids living in another country

My son is 14 and has just moved to France with his mum. We separated 6 years ago. She has sole obersorgrecht. legal ownership. We were not married.

I am English She is Swiss/Italian, he is Swiss national by passport. He has lived in Austria since 2 months old.

Austria has been the jugendamt office - apparently looking after his rights.

To my surprise, juts as he reaches 14 and is apparentlz able to decide his actins more in Austria, he is whisked off to France to live with her new boyfriend. In a new school 70km from home, Protected content from me, and during school week since he is too young to board at the school, he will be staying with a Swiss-French family with two kids also at the school

Apart from being slightly flabbergasted at this turn of events, I am looking to make the best of it for all concerned, however I do have some questions outstanding

As yet I have no addresses in France, I have been told to use his mobile phone to contact him
I have been given no school details or dates.
I have been given no outlook of when to see my son again, other than the two weeks holiday coming up in a weeks time, where we get to see my father in the UK.

I am open to ideas on this, from people who may have been through similar, or feel able to suggest strategies I might follow for my own sanity

love and peace
Nigel