Insurance cancellation and debit order stop

I phoned old mutual to cancel my insurance and i humbly requested that the next debit order of over R2000 should stop. Instead of good assistance, the guy who is and agent over the phone gave me an attitude just because i am leaving the company. So the debit order went through and i could not stop it with the standard bank app on time. This has really negatively affected my budget as I don't even know how would they refund me. Their letter for cancellations says nothing about my money being refunded.