Rudest Store Assistance

I wish i could find a zero star rating. I went to the PEP Store at Greenacres Mall in Port Elizabeth to buy a temporary cellphone to use and came across the rudest store assistant I have ever in my entire life. I showed the lady the phone I requested initially and she kindly told me to go pay while she fetches it, I did so and while activating the phone I realised it's not the phone I requested initially nor paid for. The lady helping me asked who helped me and I said the lady with the round glasses , I immediately requested the device be changed to the one I initially asked me , she starts by calling me "Nana" and then tries to force me to take the phone telling me it's for temporary use and then goes further and says I can't exchange the phone because it's against the shops policy to exchange phones (mind you I haven't left the shop and this device was changed without my own acknowledgment) She then rages and throws a minor tantrum infront of me says she's calling the manager. while she's away I explain to the other lady that I won't pay for a device I don't like and why was it exchanged without my knowledge and why did the lady at till not tell me I can't exchange it after purchase and where is my slip that states I can't exchange. The lady with the round glasses comes back and continued to call me "Nana" then says the manager is busy and she must negotiate with me to walk away with a device I don't like and don't want, she continues to force me to walk away with the device and explains to me why she changed it without informing me first , I say I'll wait for the manager and she storms to fetch another device and while I walk away she clicks her tongues and starts saying nasty things behind my back about me.

Please fix your till staff