I returned a ~$150 item to Myer a few months ago, with nothing but a transaction ID provided to me over the phone by American Express (the account had been clos

I returned a ~$150 item to Myer a few months ago, with nothing but a transaction ID provided to me over the phone by American Express (the account had been closed and I had no access to the credit card statements). It turns out that the credit card network's transaction ID is completely useless to store staff and doesn't correspond to anything they can search up. They went ahead and decided that the fact I could give them an ID number at all is sufficient proof of purchase and happily exchanged it. (Of course, in this case I was returning a defective item and they're legally obliged to replace it - perhaps they're stricter on change-of-mind.)