Duplicate Card Transaction on One Purchase

I am very upset at the service I got from Exclusive Books Walmer Park Port Elizabeth. My daughter bought a book on the 4th November 2017. The card swipe transaction went through twice, R290 + R290. I immediately went back to the shop with my daughter and spoke to a lady by the name of Ute. She informed me that the duplicate transaction will be reversed. After a week it was not done and I spoke to Ute again, who informed me that I should give it another week. She confirmed that the money of both transactions were in their Holding Account. Needless to say on the 9th December 2017 my daughter went to PE again and I spoke to a male by the name of Dillon, who informed that it would be fine if my daughter comes in to the shop and another book and we rather leave the R290 in the account of Exclusive Books. On arrival at the shop, my daughter was informed that she cannot buy a book as now no transaction has gone through to Exclusive Books account. I phoned the shop again and now had to speak to the deputy manager named Steve, who informed me that they received no money from my account and that I must now submit a bank statement to proof that the duplicate transaction went off my account. I do not understand how the employees in the same company can give such conflicting information. We are not from Port Elizabeth and cannot go to the shop as we please. The money has gone off my account twice for one purchase. All I want is for the duplicate transaction to be reversed or for my daughter to buy another book as we have paid twice for one book. I will not support Exclusive Books ever again and will give them a negative rating where I can. This is absolute poor service to the customer who supported them in abundance over the years.