How to deal with the aggressive customer?

If customer is on the telephone and is being aggressive, remain calm! Listen attentively, and perhaps repeat what the customer is saying to confirm and to reassure them that you are listening to them and that you are trying to understand the situation in order for you to resolve whatever the issue may be. 

Once the customer is done with their talk, you can then thank/apologise (dependant on the circumstance), and give them assurance that you will endeavour to resolve their problems as soon as possible. This helps them also calm down and the person who takes the call, ensure you do your job properly to resolve the issue and update the customer every so often - make note, add to your email diary that you need to give a call back until you resolve the case. 

if however, the customer in your office/store, then, in this scenario, you must be very proactive - again apply the above - calmness, listen attentively, ask questions or repeat to confirm information - sincerely apologies to the customer that they had to face such a situation and give them assurance that you will resolve this instantly to the best of your ability. 

Now as the customer is at your presence, ensure you are proactively making phone calls or liaising with your seniors if need be and request some time from the customer and offer some refreshment in order to help them reduce their aggressiveness - if you can resolve issue while the customer is in your office, good. If not and you require more time, collect customer's contact details and ensure the you contact them as you progress in resolving the issue. 

Hope this helps people out there! 

Offer him a seat and give him a glass of water apologies even it is not your fault and speak in a humble way. 

Stay calm and control your own body language, then listen to the customer’s grievance and ask question to better understand the problem. Finally find a solution for the problem.