Such Arrogance,No customer services

Yesterday i went to do my shopping at ackermans,seeing as during the week i had received an a rewards 53 voucher.I bought a red faux leather , i give my phone to the cashier so she can see the voucher number.Next thing i hear her saying she has made a mistake by selecting cash instead of credit card or something like that.So the manager is called to assist in the matter,main reason being that my a rewards voucher cannot be refunded,so they will have to ring up my purchase again with the full price.So this manager guy,i guess he is new there cuz i have never seen him before at this ackermans(i shop here atleast once or twice a month,so i think i'd know),he comes to the till and starts shouting at the cashier in full view of everyone,his attitude towards me was just as despicable,he was acting like he is doing me favour by sorting this issue out.he didnt even greet me,did not apologise for the mistake that has happened,let alone bother letting me know when my a rewards will be refunded..This guy must quit acting like he is better than everyone else,he must learn to treat his staff with respect and he must fix his attitude,he is a manage after all ,so all this must come naturally.