Pathetic Service

I bought a navy and white striped David Jones dress in Gateway branch on the 21st April and never kept the receipt as i had no intention of returning it since i was happy with the dress, a couple of days later i hand washed the dress and the navy stripes smudged on to the white stripes on just one part of the dress. On Friday the 27th i returned it because of the defect at the Pavillion branch and because i didn't have a receipt i had to wait while they phone the Gateway branch to confirm the purchase. The wait was long i ended up going shopping elsewhere and came back. I was told the purchase had been confirmed but i will only be given a voucher since i did not have a receipt. I explained that i had no intention to return the dress since i was happy with it, the only reason i returned it is because of the defect which is no fault of mine and after waiting so long to have the the purchase confirmed i did not understand why i could not get my money back. I also used my rewards card for the purchase. I was left with no choice but go leave the dress with Naven the manager as he was not helping at all. I want my money back as i feel its not fair to be asked for a receipt for a dress i had no intentionto return, i only returned it because of the defect which i had no knowledge of when i bought the dress