Two invoices overdue.

I was booked to record two voice overs for SAA. My terms and conditions were that I be paid 48 hours after recording. On their invoice they stated that it will be paid within 30 days, I had no choice to accept as they submitted it after the recording.<br> The first invoice was dated 31/08/2015 and the second was dated 03/08/2015.<br> <br> Every time I ask when payment will be done I'm told I will get back to you or early next week or the agency has not paid them.<br>