The rep is right, and the reason is that unpaid work counts as you putting value into the IRA outside the contribution rules. The prohibited-transaction rules in the tax code don't ask whether money changed hands. They ask whether a disqualified person provided services or benefit to the plan. Your labor is a service. So the faucet gets fixed by a plumber, paid from the IRA's own cash, with the invoice going to the custodian.
Disqualified person is a defined term, and the core of it is you, your spouse, your lineal ascendants and descendants (parents, kids, grandkids) and their spouses, plus any entity you control. A brother-in-law is not lineal, which is why HVAC brothers-in-law come up constantly in this room, but the answer to whether a specific person is inside or outside the line is one to run past a tax attorney or CPA who works with these accounts, because the entity-control side gets messy fast.
The part that catches people later is cash. Every expense on that house has to come out of the IRA and every dollar of rent has to go back into it. If the water heater dies and the IRA has $400 in it, you can't write a personal check to cover the difference. That's a contribution at best and a prohibited transaction at worst. People who run these accounts well keep a real reserve sitting in the IRA, not just enough for taxes and the custodian's annual fee.