Problem with landlord

Wyjaśnienie sytuacji

Hello. I lived in a room in a room in an apartment for 5 months, the owner did not write a contract with me and he did not require a deposit I sent him a bank transfer every month for the rent which was 1100zl in the last month, when I left the owner sent me a bill photo on whatsapp that I must pay an additional PLN 400 because additional use, n I said via whatsapp that the bills are fixed because that was our agreement he threatened that I have to do this now or he will go to court could he do this against me although there was no contract signed