Dissatisfied customer

I am an MTN customer who has been promised a refund after I returned the router which was not working. I havwe been calling MTN since April to date and no assistance each time I call I am go=iven a new reference number and last week an agent called Ncamisile Shange said there was R600 to bve refunded and she asked me to send her the bank statements of which I sent but today I am told that there's no refund, what happened to that money I sent an email to *** today after terminating the call with Xoliisiwe who said I should terminate the call, and her team leader will call until now no call received from the team leader. Today I was transferred from Maria to Samukelisiwe to Khanyisa and to Xolisiwe