Disappointing behaviour from Truworths representative

My 71 year old grandmother received a call from Truworths this morning it was utterly disgusting the way she spoke to her, telling her she will die bitter and harrassing an elderly my grandmother even got an asthma attack due to the devastating manner in which the lady spoke to her, I even had to jump in and the lady that was on the line did not stop even she refused to let me speak to a manager when I requested to she said I should use my own credit to call, I even said I was going to make an arrangement but that did not stop the rudeness on the call. This is so disappointing, it seems like you have no control over your employees you allow them to speak any how to senior citizens with chronic illnesses if my grandmother doesn't recover from this you will be liable for her death as the employee said that she can die... If you need to contact me contact me back on ***