Horrible customer service

I went to Jet in York Road near Pep (in Mthatha), to by a Potty chair for my daughter. I was coming from somwhere and did not have my wallet with me, I had however a R60 in pocket, I knew the potty chair wasn't more than that as I had been to the Jet a few days prior. I get to Jet see the Potty chair is R49.99, I take it and go wait in line, while in line I see a small fridge near the till for R8.99, I take one take a sip and go to the cashier, the cashier then says the water is R10.99 and I owe a extra R1.00. I tell her the water is advertised as R8.99 and she can go have a look as its one foot away from her. She refuses, I ask for the supervisor or manager. She refuses, I explain I didnt come with my wallet and only have R60 and its not my fault they never advertised the water correctly. This cashier named "Tantsi" refuses to assist me. I walk in the boiling sun to my work place for a F*#ken R1, come back pay and still recieve attitude!!!! You guys need to explain to that women what customer service is!!!!