Wrong shoe sizes in BOX

i am very upset i bought a pair of SHOES at Panther to the value of R300, i found the 1 foot being very tight i wore the shoe twice and it will still hurting my foot alot to a point where i couldnt stand it anymore, i for some reason checked the sizes of the shoes, the shoe that i have fitted on was my size but the shoe in the boks was a smaller size i then called the shop and told the lady that the shoe sizes in the box was wrong, she admits this to me because she is now sitting with the two odd sizes, i asked if i can come swop it out although i have worn my shoe already i called and message several times with no reply from her. i am now the loser of R300 sitting with shoes i cant wear, i would ike to be contacted and reinburst if that is teh case because this sales lady called Ilsa is now ignoring me and for such a up market shoe store this is appauling....