Outsurance
Cancelation confirmation

I phoned roughly an hour after i took the policy for car insurance to cancel it.
Reason being i got it at less than half the price from standard bank.
I asked the person (Eric) to send me confirmation that my insurance has been cancelled.
He said it can only be cancelled on the first of September (the same date my first debit order is suppose to go off)
he ensured me that no money will be taken from my account, yet i am skeptical now because why do i not get a letter of confirmation that it has been cancelled?
I did explain to him that the reason i want proof is for in case an error occurs and the money does get deducted from my account, i will have some form of proof.
How is a brochure going to help me in this situation?