Delay in refund

I placed an order with OneCart and after realising that my order was late I proceeded to contact their call centre. I was then told that my account was flagged and they are still waiting for the outcome of a investigate. Mpumelelo who was handling my query promised to give me feedback. After a lot of back and forth I was finally told that it was a system error as there was nothing suspicious with my account. So now I've requested for a refund and was told its only gonna take 30 minutes. Its more than 3 days later and I'm still waiting for my refund. They are ignoring my emails and whatsapp messages.