bad bad service in american swiss mall of africa

I bought a ring month end of July for my boyfriend at American Swiss mall of Africa and second week I took it back and i have lost the slip however I bought the ring with TFG account. I took my statement to show them that i bought the ring there. and requested for a refund a the ring didn't fit him. poor service coming for a manager imagine she refused to help me because I lost the slip and on the statement she says she could see that i have bought something there but it doesn't look like its the ring because that ring worth the price on my slip its more expensive than the amount on the statement. but how is that my problem because I came to buy as a customer and paid what I was told by the consultant. i'm so freaking mad and i didnt expect this poor service from american swiss mall of africa they even hire *****'s because they capture wrong prices and now we are the one to pay for there inconsistency