There can't be a mistake if there's no bill; errors only occur when there is one.
"Brother, I remember not paying this rent. At the time, I was puzzled why they didn't charge me for this quarter. Turns out they made a mistake. So, brother, you refunded me too much."
"Not only this quarter, but it seems I also didn't pay for a couple of months. However, I can't remember clearly. Let me think about it slowly, and once I remember, I'll tell you. This way, you can cross-check the records again, and I won't feel guilty for taking more of your money."
"Otherwise, if one day you find out, I'm afraid you'll kick me out."
With Tianna addressing him as brother repeatedly, he should understand her intentions by now, right?
From time to time, Tianna took a glance at Yigol's reaction. He no longer looked as gentle as he did previously. Could it be that the drug in the perfume had finally taken effect?