Exchange policy sucks

I purchased a very expensive LEGO for my son for his birthday to the value of R2700 at Toys R Us Fourways Mall. As kids are won’t to do, he changed his mine about what he wanted. Unfortunately it was a month later and we had shredded the credit card slip. I have proof Of the amount and the transaction date on my credit card statement, and even provided the bank statement and. Card number. They refused to refund and would only exchange which does not help me as my son wants is not at Toys R Us. I understand if I couldn’t produce proof of purchase but I could. Nothing had been opened, I go to about 30 kids parties a year at an average of R500 a present. I will NEVER step in one of your stores again!!!