Standard bad appalling service

I am absolutely appalled at the service I have received from Standard bank. I have, on two occasions purchased R10 airtime on their mobile app, my account was debited and never received the airtime. When I told them about the issue, I was informed I needed to contact the Call Center , but how do I contact the call center when I don’t have the airtime to.

My issue is still no resolved. Standard bank took my money.