Wallapop charges appear with the following nomenclature: MGP * WALLAPOP.
If you have a charge on your card that you do not recognize, it may be a pre-authorization from the bank. For more information, you can read this article: When is an offer charged?
We also recommend that you verify that no one in your immediate environment (family, friends or co-workers) has used the card to make this payment.
On the other hand, if applicable, you should ask your bank to cancel the card to prevent it from being misused.
If it is not one of the above cases, we recommend that you file a complaint with the appropriate authorities and they will contact us to provide them with the information they may need.