Refund policy

Wife bought a garment, from Donna, East rand Mall on 6th Dec. Returned goods 12 Dec but without cash slip, showed proof of purchase on card statement and was promptly told that no refund to my bank account could be done without the slip. Even though I showed them the proof of purchase on the actual account. I then had to take a voucher to the value which still keeps my R499. 00 within the group. This is unacceptable and I demand action.