Increase energy charge of fixed contract

Hello,

In a discussion with a junior colleague (both of us are expats). It was mentioned that her landlord increased her charges via email based due to high increase in energy costs. Failure to do so will be considered a breach of contract.

Looking at her contract, it is a fixed term and fixed costs with no clauses for price / costs increases. Therefore, what the landlord has requested is not correct in my opinion. As pricing can only be changed at end of the contract term.

However, I am not sure if in Brussels if any special provisions/allowances made recently due to the current situation. I cannot imagine this can be as it would invalidate existing contracts.

Thus am I correct in my understanding that such charges are inappropriate? If so, would it be possible to reclaim charges or already too late if the first additional has been made (therefore tacit agreement).

To be fair, it will be tricky when the contract ends unless a change in accommodation will take place.

Thank you.