Extremely bad service at Clicks Vincent Park

I had an extremely bad service at Clicks in Vincent Park, on the 3rd of October 2020,I was shocked to the core. Firstly the cashier that was assisting me had absolutely No idea that Portia M is currently running a 3 for 2 special, this special is been running all year long, she asked me if I could go with her and show her the aisle where I got the products from as she is not aware of the special. To cut the long story short I was over charged, I ended up not getting the 3rd product for free, I explained more than 3 times to this lady that she's not supposed to charge me for the 3rd facial product, she couldn't understand, I was running late for a meeting and I had to leave.. I decided to call the manager right after I left the shop and explained to him what had happened.. He then promised to investigate and get back to me. After the investigation was done they then agreed that there's indeed an amount that is due to me, what puzzles me is that they are asking me to go to their store after I have explained to them that I was only in east london for the weekend, I am based in port Elizabeth.