Hacked instagram account

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Hello,
We are an association, and our instagram account has been hacked.
We still have access to our Facebook page which is connected with it (I see it in the administration page).
The hackers' team has declared taking control of a set of accounts, among which ours. They changed the profile with their slogan, and publish personal information.
They changed the password and the email.
Now I don't know where to reclaim? I found a phone, an email of instagram but nothing seems work.
Thank you in advance.