How can I update my apps without a credit card

Why do you think that you need a card on the account ? Are you getting an error message when trying to download updates ?

If you currently have an invalid card on the account see if you can remove it : Change or remove your Apple ID payment information in the iTunes Store - Apple Support

If you don't get the 'none' option on the payment details screen : Why can’t I select None when I edit my Apple ID payment information? - Apple Support

Purchases are considered final but you could try the 'report a problem' page to contact iTunes Support and see if they will refund or credit you as a one-off : http://reportaproblem.apple.com

Or you can try contacting iTunes Support via : https://support.apple.com/contact or https://www.apple.com/emea/support/itunes/contact.html

You will either have to pay what you owe (e.g. by putting a valid payment method on the account), or contact iTunes Support and see if they will cancel it as a one-off - until you've paid it, or it's been cancelled, you won't be able to download anything else.