It's October. Your tenant in Flat 2 says he paid ₦600,000 in March. You have a bank alert with no note, a voice message you can't find, and a caretaker who thinks he remembers. He has nothing either.
Half of it came from his brother's account. The alert just says CHINEDU O. You've been guessing which flat that was for ever since.
Nobody has to be lying for this to go wrong. There's simply no record either of you can point to.