Shrunken clothing

I bought a lovely top from Mr Price Sport Centurion, over the weekend. The top fit nicely coming down to my knees, thus making ot appropriate for work etc. I washed the top in cool water only to find it shrunk a lot! It is now basically too small to wear! Even though I have the receipt (it was emailed to me) I dont have the tag. Can I still return it? Help Mr price team...