Bitmex drained my BTC account

I recently discovered that my BitMEX accounts were charged 0.1 BTC for inactivity fees over the past two years.

I saw an unopened email from 2022 stating:

|| || |As an unverified BitMEX user, we're writing to let you know that account fee changes are coming.|

|| || |Why? It's been a year and a half since we announced that each and every BitMEX user needs to be verified. To further support that initiative, an increase of the monthly account fee to 0.002 XBT or 1% of your account balance (whichever is greater), will be charged going forward. This will include the July account fee, which is charged at the end of the month. |

Is this legal? Especially in the EU? I pinged their support and got told exactly that and they promptly ended the discussion. I'm thinking of taking legal action at this point but unsure how to do this. This is infuriating.