Speed point issue

Good day

It’s been a week now since a customer swiped at our speed point for his purchase using a Nedbank card, we haven’t receive our funds to the business account.Yesterday went to my bank Fnb where I opened my fnb business account, they told me must call the client ,so can’t get hold of the client but have the approval slip with me. Which I don’t understand what to do cause I’m on the losing side we’re the client got his goods and I haven’t got my money.

Please advise me what to do