Try to trick them into send you a text or email saying yes you did orally informed them.
It reallly depend on the judge, your argument is that the contract is contract of adhesion containing some unfair provisions, amount to some kind of unfair business practice. A more reasonable clause or practice would be when you orally informed them of termination, they ask you to fill out a form and leave with the front desk.
It's not unreasonable to ask you to notify them in writing (such as fill out a form), it's unreasonable for them to require you to send them a certified mail.