Lay-by cancellation

I did a lay•by on the 2nd of June and on the 28 June ,I went back to the store to cancel the lay-by because I already bought the shoes ,they refuse to refund me,they want me to take a voucher and you buy by choice not by force if I don't want to buy anymore it's my choice ,I don't want a voucher,I would understand if the lay-by expired.i don't think I will ever go buy shoes at solo ever again ,when you lay-by no one tells you if you cancel you won't get your money back,so that when you layby is at your own risk,so disappointed.