Is there a way to cancel transactions and withdraw the funds?
Crypto transactions are irreversible, once you have sent them you can't reverse it or retrieve it unless the receiver will send it back to you. Some transactions on the Ethereum network are failing and it's about an issue through contract addresses so that's the chance that your transaction can be canceled. Bitcoin isn't like PayPal that you can reverse transactions and asks PayPal's management to cancel any transaction that you have done.