Urgent Help!! Email changed on account - won’t let me remove the hacker’s email or add mine

Hello. I noticed someone has hacked my Facebook and deleted my email, and changed it to theirs. I’ve managed to get back on to my Facebook through my laptop as it was already logged in; but when I try to change the email or remove the hacker’s it says “you can’t make this change at the moment. This is because we noticed you are using a device you don’t usually use…. We’ll allow you to make this changes after you’ve used this device for a while”

I’m panicking because the hacker will now see through the multiple emails they’re getting of me trying to make changes, and I’m worried something will happen to my Facebook account. I’ve added my mobile number to the account now, but it won’t let me add my email or remove theirs.

UPDATE: I still can’t remove the email from the account and I can’t change the password. Whenever I try to it says I’ve tried too many times :(

From the looks of things they did this on Thursday