Rude Indian Manager with no discretion

I purchased a dress from Edgars yesterday at 9:30am I took it home and found that it didnt fit , I then today during my lunch break took it to return it, however Edgars refused to exchange my item the manager there an indian women with short hair dark in complexion wearing dark lipstick told me that the dress cannot be refunded as they cannot put it back on the floor as it has "marks" the marks she was referring to was body powder from my body when i tried it on it was my mistake that i didnt rub it off however she imp**** that i wore the dress which is not the case firstly yes i could see the powder marks however implying that I wore the dress is extremely insulting as i was exchanging it for a size bigger which means the dress didnt fit me to have worn it secondly I picked up the bigger size which also had marks on the front which also looked liked powder marks however because I liked it decided to overlook that fact and take the dress. If I the customer can make such a discretionary decision as to know that although the dress had a mark i was still willing to take it because it it is very sad that your so called manager cannot use her discretion I am extremely unsatisfied with the service as there is no training clearly been put in place the manager should actually use her discretion before making any statements implying that i wore the dress and also the fact when I asked her what about the marks on the front of the dress that im taking her answer was that "i dont know" and my marks are on the inside shoulder of the dress. you could tell that it was powder as i even showed her on my body at the very moment I was wearing baby powder she still refused I am sure if i take the dress to another store there will actually be a qualified manager there who can assist me as I dont believe that edgars has *********** staff , however one in particular. this is very bad business as I purchase clothing from Truworths who actually took a pair of shoes that i wore back because it was uncomfortable also same policy at Spitz, London I am extremely upset that i was accused by the Indian female manager at Edgars pavillion I could have not worn the dress if it didn't fit me, also as a customer i used my discretion when seeing the marks on the bigger size so there should not be any excuses coming from the manager in my opinion she should be demoted as she is extremely rude and incorrect decisions are made