Certainly, "Tortious interference" comes to mind.
While it's a difficult one to prove, there are typically 6 elements:
- The existence of a contractual relationship or beneficial business relationship between two parties (possible problem here).
- Knowledge of that relationship by a third party.
- Intent of the third party to induce a party to the relationship to breach the relationship. (or refuse to enter one).
- Lack of any privilege on the part of the third party to induce such a breach. (no right to do so via some other aspect of law).
- The contractual relationship is breached. (the normally-accessible-to-anyone transaction is prevented).
- Damage to the party against whom the breach occurs
The only real "stretch" here is that Tortious Interference is written for cases where you already have an existing business relationship or contract in place. You're talking about a situation where a vendor normally proffers its service to any member of the public, and you'd argue there's an implied contract that they do business with any comer.
In real estate particularly, it gets a lot more complicated because of Fair Housing laws. The apartment could get in big trouble being caught refusing to do business with someone, if the reason for the refusal was sourced in something related to race, creed, religion, sexual orientation and a bunch of other no-no's.
Even if that's not your motive, if they (plural: victim and attorney) can convince a judge or jury that it is your motive, you and the apartment could owe them a lot of money.
Fun fact: conspiracy to commit a Federal crime is a felony, even if the crime isn't.
Regardless... I think if you are paying the vendor to snub the customer, courts would find that to be a perverse and unjustifiable behavior, and would see harm in that, especially if it was part of a pattern of behavior that constituted harassment. They would tend to assume the worst motives unless you could show other motives.
I suspect they could even get a restraining order blocking you from interfering in their business relationships anywhere.
You would also be subject to discovery, and would be compelled to disclose anywhere else you interfered, and pretty much anything they want to ask you. You can't refuse to answer ... unless ... your answer would incriminate you of a crime. But that's the kiss of death in a civil trial, because the jury hears that, and infers you are a crook. Game over lol.