Having regular interactions with the client are a part of the day-to-day business of a Project Manager Professional (PMP). Occasionally, a client’s behavior may fall short of what are considered to be standard norms, be downright aggressive, and the person dealing with the client, in this case the manager has to bear the brunt of that less than cordial attitude. A major part of the challenge that a project manager faces is catering to the very many different kinds of people that he may deal with and yet not being pulled in opposite directions.
It can be increasingly frustrating having to deal with someone who is overbearing, unsure yet opinionated, so set in their ways that they are entirely unwilling to negotiate. To tackle situations as such, the manager needs to take control and do something. One thing you can be absolutely sure of is, is if the client is allowed to steamroll, badger and bully you into something and you don’t do anything to put an end to it, it will continue on endlessly. Time for a Change! No matter how difficult, you need to know how to effectively deal with aggressive and assertiveness of the client to prevent the situation from escalating, and getting completely out of hand. Here’s how:

Maintain Composure
The first rule in facing an unreasonable client and dealing with anyone’s hostile behavior is to keep absolutely calm. The better your control on your emotions and the less reactive you are, the better judgment you can use in handling the situation. Maintain an open and relaxed posture to appear less confrontational, keep your voice down and empathize.
Listen Carefully
The next step, when you feel that the client may have settled enough to rationally talk, is to listen carefully. Never blame the client outright even if he is responsible for the circumstances. Never dismiss, instead always try to validate the client’s feelings. Do get as much specific information that you possibly can. The client may not be very clear in what the problem is so you have to be careful in understanding what the client means. If you cut of the client in between or point out their wrong-doings, you not only will not be able to get to a rational solution but will also inspire more anger and defensiveness.

Diffuse the Situation
To appear sympathetic to the client and quickly diffuse the hostility of the situation and prevent it from escalating to a verbal bloodbath, apologize and agree where you can to acknowledge they’re ideas. It will immediately make the client feel like you are considerate and understand their position. Follow this by reassurance. Be precise and clear in what it is that you can do to help the client.

Reason and Resolve
Although there is no real defense against irrationality, negotiate where you can, with persuasive arguments that cement your standing. Respectfully share your position while offering some flexibility. Use phrases that soften your approach such as ‘the way I see it… ‘, ‘the company’s position on this is… ‘
However, avoid agreeing to something that you cannot deliver, or outside your contractual scope if it has a big impact. Be specific, direct and confident in your ability to communicate. Offer something for the future. Agree on improvements, to accommodate and reach a compromise.
Often the best way to deal with aggressive clients in any given circumstance is to be assertive. Deal with aggressive and antagonistic people, stand your ground if the contract is on your side. Say what you have to say and don’t give away promises just to avoid conflict. Pretending a problem isn’t there to evade confrontation will only end in a clients walking all over you with unreasonable demands.
http://jobmasternigeria.org/dealing-aggressive-clients-project-environment/