Debt Collector

Debt Collector is a side quest in Fallout: New Vegas.

Detailed walkthrough
Talk to Francine Garret at the Atomic Wrangler, and ask if she needs any work done. She will inform the Courier that there are three individuals in Freeside that owe the casino caps. In total, it will be 600 caps owed, and the player character will gain 150 caps if they return the caps to Francine (300 with a Speech or Barter check of 35). The three individuals are Grecks, Santiago, and Lady Jane. It is also possible for the player character to pay off the debt themselves.
 * Grecks owes 138 caps and is located behind the Old Mormon Fort.
 * He will pay up the 138 caps as soon as he understands that the Courier was sent by the Garrets. Passing a Speech check of 40 will cause him to give another 41 caps, and a subsequent Speech check of 60 will cause him to give the dirty pre-War casualwear he was wearing (-25 Karma).
 * Repeatedly commenting about his eye will turn him hostile, allowing the player character to kill him (Freeside Infamy) and collect the debt from his corpse (a bag of bottle caps containing 153 caps).
 * Santiago owes 212 caps and is located behind the collapsed building opposite Mick & Ralph's. He will try to talk his way out of it, but the options to get the caps are ultimately unaffected.
 * Punch him in the face (in dialogue) or threaten to "Collect from his corpse" will get him to pay up the 212 caps.
 * Passing a Speech check of 50 saying that "Francine put a bounty on his head" will cause him to give 256 caps.
 * If the quest Wang Dang Atomic Tango is currently active, one can convince him to work off his debt at the Atomic Wrangler, also completing the suave talker part of that quest. Doing this, one will only have to return to Francine with the 388 caps from the other two, but will still get the full reward for collecting the debts.
 * This option will not be available if a suave talker is already found before talking to Santiago.
 * Santiago does not have dialogue options to turn hostile, but one can still kill him and collect the debt from his corpse (a bag of bottle caps containing 256 caps).
 * Lady Jane owes 250 caps and is located to the right of the Strip North Gate.
 * With a Perception of 7 or higher, the player character will be able to tell that she is lying and get 250 caps.
 * Through a Speech or Barter check of 40, one could also ask for other things to help pay off the debt. Doing this results in her handing over 156 caps, 3 sensor modules and 2 cartons of cigarettes (the items have a total base worth of 170 caps).
 * With the Lady Killer perk, one could convince her to hand over the 250 caps owed, as well as giving out the location of her lost caravan.
 * If one fails the Barter and/or Speech check, another option will show up which says "Just give me what you have on you and they might accept it knowing you're dead." From here, one can either accept the 156 caps she is willing to give or choose to attack. Choosing to attack will turn her hostile, allowing the player character to kill her and collect the debt from her corpse (a bag of bottle caps containing 256 caps).
 * Lastly, one could offer to retrieve the caps from her lost caravan in the broc flower cave. Jane's brahmin inside the cave will have 276 caps on it.
 * The brahmin will not spawn if the cave has been entered before receiving this quest.
 * The brahmin also will not spawn unless one offers to retrieve the debt this way, or getting the information through Lady Killer.

Once these three are taken care of, Francine will have a fourth assignment. Her former collector, Caleb McCaffery, skipped town with a large sum of caps, and she wants him dead. His hat needs to be taken as proof of killing.
 * Caleb is in the first section of the Strip, just outside Gomorrah (note that one does not simply walk into the Strip initially. See here for possible ways of entry).
 * With a Speech check of 40, he will give the player character his hat and a portion of the stolen caps (57 caps).
 * Any other dialogue option will turn him hostile and therefore the Courier must kill him to obtain his hat.
 * On consoles, a major bug may render the game essentially unbeatable if Caleb is killed. See the Bugs section for details.

Reward
Bringing the hat back to Francine will finish the quest, earning 150 or 300 caps depending on the initial Barter or Speech check of 35, and Freeside Fame.

Behind the scenes

 * Various dialogue topics refer to Santiago as "Angelo" and "Sancho".