Pathetic Customer Service- to say the least

On Saturday around 1 pm, me and my hubby went to buy an hp printer at the Rustenburg mall. The lady at the till (Keitumetse) Captuted an incorrect amount, R100 extra to be exact. When I asked her why there is a difference in the amount, she then gave me attitude and continued to process the transaction. I then called the salesman that was assisting us initially, he had no name tag. He called Glenda (who I assumed is the supervisor), She took the slip with her and never said anything, then she disappeared with the salesman, 10 minutes while waiting, with no one informing us as to what is happening. I went to Glenda and asked her if they are assisting us or not. Then the salesman called us to another department where there were 2 ladies to assist us.Now these ladies had their name tags turned around(invisible). They then said they are giving us a voucher of R100, we refused the voucher, because this was not our fault that they captured the wrong amounts. They said nothing and asked us to sign on the dotted line, which we refused. Only when I told them that I am taking this to Hello Peter were we then advised that they will process the money back to the card.