soiled T-Shirt

I Recently purchased a T-Shirt from Woolworths in Chatsworth, not realizing that the size was incorrect. When I decided to return it I was told that the t-shirt is 'SOILED', according to the manager and dna testing?? I really didn't know Woolworths did analysis like that? that's great, please don't use the dna technology to fight crime in S.A, because I defiantly did not use the shirt.so much for your results. Secondly why must I be questioned as to why I purchased a size bigger? must I consult the sales lady when I wish to buy clothes and why? I think this is really pathetic at the way I am being made feel for a R160 shirt, Im a professional, I don't need to use cheap tricks for using a shirt for a day. Its either you guys better equip your staff to deal with complaints of this nature or use the shirt as a display for a mannequin sponsored on my behalf. thanks for the 'fantastic service' well done!!!!! really I would like to hear of a way forward because im sitting with a shirt that is of no use to me!!