Does not want to give refund

On 25/07/15 a Telkom technician named Mike came out to fix my line. Mike told me that the problem is my modem. I immediately went to go buy a new modem at Telkom Cresta. After testing the modem it turned out that the problem was not my existing modem. So on Sunday 26/07/2015 i went to return the modem, But the sales person and the manager Mr. Matthews insisted that they cannot refund the modem because they do not have any cash.<br> <br> What type of business cannot refund there clients? This is ridiculous.<br> <br> Anyway we agreed that they will deposit the refund into my back account by 3pm 26/07/15 before they close.<br> <br> At the time of this writing it is Thursday (30/07/15) and i still have not received my refund or any feedback.