Bad Service at Game N1 City

On the 23/06/2018 I went to Game Store at N1 City,Goodwood and purchased a Huawei P Smart Gold,upon my purchase,the consultant by the name of Sven Abrahams assisted me,he then opened the phone,without asking me if he could as he says he had to test it.He then put it back in the box,he also advised me a 7 day return policy,I took the phone and left.I never used the phone,as i have decided that don't need it anymore.Today the 25/06/2018,I went to return the phone,and I was told that I cannot return the phone as it was opened,when in actual fact he was the one that opened it on the day of purchase,and I also advised him that I never even used it.He then proceeded to go fetch his manager by the name of Adam,and he also advised me the same thing as Sven.According to the t&c's on the receipt "if you have changed your mind,bring it back in an unused condition in the original packaging" of which i have,and rather states that "we will either exchange it or refund you,within 30 days"