Help: My €10/month NOS subscription just billed me €443 for August. How do I dispute and cancel?

I am formally requesting the immediate termination of my NOS mobile subscription and disputing the recent unauthorized charges on my account.

My agreed-upon contract is a €10/month student plan. However, I am now being billed over €400. This is completely unacceptable, especially considering I submitted all required documents a month ago and my SIM card has been closed and inactive for the entire month.

I am a student and cannot afford these erroneous cartoons. Please terminate my subscription immediately today to prevent further billing, and provide a full explanation for how a €10 subscription resulted in a €400 invoice.