Rude behaviour from staff

My mum is a longstanding customer who taken ill and we provided medical reports as requested to rcs to.close her account. She is on pension as her only income now. She received a call today at 9.27 from a *** lady at rcs. My mum speech is impaired and she she was so rude said my mum is blabbering and cut the call. This is how RCS treats customers?? Absolutely disgusting behaviour.