I've noticed lately traders are impatient, expecting payment asap likely only a couple of hours after winning the auction. Does trademe allow up to 7 days? Its so frustrating because they place unnecessary negative feedback and I've got over 130 positive feedback

I sold an item on trademe in early June, this morning i got an email from someone saying they haven't got the item yet. I said i didnt sell you anything recently and sent a screenshot from nz post tracking saying delivered 7th of June. The person replied implying they bought something from me last week. I sold one last week to someone in Dunedin and he emailed me to confirm the parcel arrived. Do i ignore this person claiming i haven't sent them this item? I don't understand this