In interpersonal communication use the three-part management strategy (state my feelings, describe the other person's behavior that I object to, and state a cooperative response that we both can live with) for: 1. My friend helped me get a job at his company. He reminds me every time he needs something and tells me if it wasn't for him I wouldn't have a job here. 2.Someone who is always making statements like, "You can't be serious!" and "You've got to be kidding" whenever I talk about a promotion or making plans.

Interpersonal communication strategies are useful in making it possible to talk to somebody about a conflict. In your question you listed three parts of a strategy designed to accomplish this without letting emotions or defensiveness get in the way. Here's how I would deal with each of the two scenarios using this method.
Scenario 1
State your feelings:
It is important to acknowledge the other person's feelings right away. People are naturally defensive, so your first job is to soften that a little, even before you state your own feelings. I'd say something like: “I really appreciate you helping me get this job, but right now I'm responsible for doing xyz. I'll help you if I can once I've done what I am required to do.”
Describe the other person's behavior:
“When you say that if it wasn't for you I wouldn't have this job, you make it sound like you don't think I'm doing the job well enough to deserve it. That's not what you mean, is it?”
State a cooperative response that you both could live with:
Try to offer them something they want if you can, but still be firm about doing what you have to do.
“I'll be glad to help you whenever I can, but I have to make sure I complete my job properly first. “
Scenario 2
State your feelings:
“I thought I was doing a good enough job to deserve a promotion.”
Describe the other person's behavior:
This time, since they've been making negative comments, give them a chance to offer some input.
“Your comments make it sound like I'm doing something wrong. Do you think I need to improve in some area before I should seek a promotion.”
State a cooperative response that you both could live with:
Show a willingness to cooperate.
“I'll be glad to think about how to improve in whatever areas you mention.”
Notice that in both of these scenarios, we are acknowledging the other person's feelings and views respectfully, while giving them a chance to respond. It isn't just a matter of saying something like “Hey, listen here buddy. You're going to stop doing this and that's all there is to it.”
Also, we can't always expect these types of conflicts to be solved immediately. It may seem at first like you have been unsuccessful, but sometimes, after people have had a chance to mull things in their mind for awhile, they will change their behavior, if you stay calm and courteous.