Exploit vulnerability

I paid the proforma invoice of R5200 for urgent oxygen supplies for my husband suffering from Covid. The oxygen was not supp**** in the agreed period and I had to cancel the order. I am trying to arrange a refund and provided banking details but the company secretary are only interested in more sales and hang up the phone as soon as she hears my voice. My emails are also ignored. I feel exploited since I was desperate for this service and now I need to fight to get my money back with my husband still in desperate need of oxygen.