Horrible Attitude towards customers and colleagues

I bought plasters and as soon as i left the shop opened them only to find out they were not a size i wanted, so I decided to return them for an exchange of the ones I wanted. The lady at the till who was assisting me was so friendly and willing to help but said she needs to call her supervisor for authorisation. She called Sibongile and as soon as she got to the till i was being assisted at 1. Didnt bother to greet me 2. All she did was give me one look and pulled a very serious and rude face 3. As the cashier was explaining to her that i was returning the goods, she was just not interested in the story and kept on dismissing the cashier in a very bad manner (Showing no respect at all to her in front of me). Then the last straw was when the cashier says to her \She purchased the goods bby redeeming her points and now there is a difference of R1.50 due to her so should I"...she couldnt even complete the sentence cos all Sibongile did was walk away and shout as she was walking \""Just give her R1.50\"". I felt undermined as a customer and disrespected!!! I even asked the cashier why her supervisor is so rude and the poor cashier just shrugged her shoulders in a way of saying she doenst """