Vodacom is *******

I made a cash payment on my account with the correct ref number and then vodacom debit again so it was a double payment. I requested a refund and they said that I need pop even though it shows on their system that I paid with the reference number. I have been with vodacom more than 12 years and this is the first time that I had to send a proof of payment to them. And now I lost R2000. I see vodacom now as ******* and *****s.