Confused Buyer

On the 01/06/2018 I bought material at Buco that is worth R2 646, I then told them I will come back an fetch them after a week as I had to get a pickup truck, unfortunately I lost my receipt, I then went back to them explain the situation and told them that I can even print my bank statement to show them the proof, they told me without a receipt there is nothing they can do, as my bank statement won't prove whether I hd taken my good or not. late June 2019 I found my receipt inside a pile of my books, went back to them explain the situation, and the delivery slip still attached to my receipt and not sight, the lady I spoke to promised to give me a call as the manager was not in, I waited for two months for the call I decided to go back again, I got the manager he looked at the documentation he could see that nothing was taken but told me that they change the system and he had to contact head office, he also promised to give me a call, after a month no call, I went back again the manager was off, after numerous time trying to contact the manger I finally got him he told me that there is nothing they can do despite the fact that my documents are in order, I fail to understand that they could not assist me without my receipt as nothing can be proved and yet can't help me with it, I even said to them I'm not looking for a refund anything of the same value that I can but from the shop I will