return policy of textbooks not objectively used

On the 29/01/2016 I bought a text book which costs me R930 from Van Schalk book shop at Long street Cape Town, on the 4/2/16I opened the book pages through and compare it with my study guide,only to find that I bought a wrong edition (Project Manegement the Magegerial Process 6th Edition).Iimmediately called Van Schalk bookshop to inform them about my predicament, I was told the policy allow that within 10days,since I stay about 100km from Cape Town I arranged that I will bring it back on the 6/02/2016. Indeed I went to see them, upon arrival I was referred to some lady who suppose the be the manager,she just looked at the book, pointed me at the door to the return policy which states that the books will not be accepted if the pages are damaged,tried to ask her to show me where the pages are damaged because I only went through the book once and the bent of the cover is due to the design of the cover,she just raised her voice towards and asked me how is she suppose to sell the book like that,since I am the one desperate and she didnt even bother to consider my explanation.I just left the shop and drove to Rondebosch Van Schalk where I bought other new textbook for other R936.