Pathetic Service!!

I made a purchase on Pick n Pay online. I made a mistake with 2 items and have been struggling for 2 weeks trying to exchange my items!!! I don't have the option online to do so, I was instucted by the call centre agent that ANY pnp can exchange my item when doing so pnp advised that the call centre advise them that only ANY pnp Hyper market can exchange my items when doing so PNP Hyper Market in Vanderbiljpark advised they cannot assit me as it was purchased online at PNP in Heidelberg and needs to be exhanged there or Online! No one can assist with exhanges and I have been sent from pillar to post with no assistance from PNP!!!!! They have horrible service all round I will NEVER purchase an item from PNP again!!! They are useless!!