Thank you for your question
My name is Clare
I shall do my best to help you but I need some further information first
How far in advance are you aware of his visits?
How far has the REMO process gone
Does he have a Uk bank account?
Do you know where he will be staying in December?
You should suspend the REMO system for now - it is an either or process.
You should then apply to the Family court for a Judgement Summons
and seek a hearing date during the period you know that he will be in the UK.
Your ex will then have to pay, or not return to the UK, of face prison.
You can read more about the process here
I hope that this is of assistance - please ask if you need further details