Vinted debited my money?

Hello, I sold a witch costume on Vinted. This costume cost 8 euros. She wanted to pay me via Vinted with my phone number… Then I was asked for the card number and the amount of money on the card to verify that it was my card. After that, I received a message from the bank. The amount was 304 euros, and I did this twice. Then I asked the Vinted supporter three times what the 304 euros was. They replied that the amount had nothing to do with my account. Instead of the 8 euros being added, 304 euros were deducted. Can anyone help me get the money back?