Miro Charged Me After Free Trial Without Using It – Need Help to Cancel and Refund

3 weeks ago I tried the free trial of Miro using a debit card. But then today a bill appeared on my bank account. When I wanted to cancel, I was charged, even though I didn't use the account. I want to cancel because I don't need it anymore and don't want to use it. How do I cancel without being charged? I can't afford it