MOSTAFA Are we talking about card payments or direct debits here? They're two different things.
For direct debits, you can always decline them. And if you have paid a direct debit to a company earlier and set it to automatic acceptance, you can remove this automatic acceptance by going to the relevant sub-account, opening the Settings at the top right, then click on Automatically Accepted Direct Debits and manage them from there.
With card payments, merchants can generally just charge your card without needing prior approval every time from you. You could freeze or block the card completely, but this also affects other subscriptions that you're using that card for. And it might be a hassle to setup a new card. Therefore, it's best to contact the merchant and ask them directly about the charges. They can refund them if they charged you in error.
