Well, I did.
As we have a 1 year contract, the guy just told me "You must give me your Resignation Letter and only after 1 month you can stop."
I didn't give any letter as I was waiting to get paid.
Well, in the beginning of the year he came with this completely different conversation saying "You know you're not working with us any more from next week...", and that he "accepted" my verbal notice.
More, he told me on Friday 2 January when the last day of our rota was Sunday 4 January.
I still fought back demanding at least 1 week notice as it says in the contract. He agreed and said he would talk to the boss.