Have you ever been unable to help the customer with their problem? How did you deal with this?

Honestly many times. The most suitable and appropriate solution is to kindly refer them to your superiors because sometimes it might be a very complex, technical, private issue, sensitive issue of which you might not be in position to handle. Also don't lie to the customer or keep them waiting for a very long time but immediately and kindly refer them to your superiors. On the other hand, if the situation is in your reach but you aren't sure enough of what to do, make some quick consultations from experts around, your team members or superiors and don't let the customer think your aren't knowledgeable or may be that you are incompetent. Thanx for the invitation.

Very rarely I have come across to some impertinent customers for whom I appeared to be unhelpful. It is an integral part of my work ethic to help the customers all through the way. But no matter how unpleasant those situations were, all of those were great learning experiences to deal with them. I usually record their requirements in a form of video, document it and channelize it to the higher-ups for looking after those issues or for formulating better helping suggestions.

Be Empathetic. One of the quickest ways to calm an angry or difficult patient is by being empathetic

Nope, never happened, nah, final answer!

And if it ever happens I will use all my soft skills and get the answer from the manager or engaged him while he/she is resolving the issue and next time I will be fully prepared for the situation to handle it by myself.

tell that I can not help in a simple way 

Yes reallyWhen the product is out warrantyThe client is informed because I can not solve his problem.Explain the terms of the warranty and apologize for not being able to resolve the problemIn a decent way

yes i do.@ its not bad to say sorry a simple as that @ giving information can be solve by them for the matters they are facing of

I wasn't unable to help any customer with their problems or needs. In fact I suggest that, if any customer is angry and frustrated about any services of the company, take the following steps -

1. Calm the client, speak politely and listen carefully to what they have to say.
2. If the problem can be solved within your scope, do it deligently.
3. If the problem needs to be escalted to higher authority, then, give the client your honest suggestions, exchange your cards/contact number with the client and make sure the problems get solved at the earliest

No but I had an experience where customer came with warranty issue and my dealer ship denied to give warranty but the customer concern was genuine so I stood for him and negotiate for the customer with my employer and they replaced his vehicle part in warranty. 

but in some cases where warranty claim will reject by the dealership because of rough use or they fail to do the periodic services. in that situation you have to stand with your dealer ship (Employer) and negotiate with the customer and educate him why warranty was denied by the dealership or manufacturer. I mean to say that don't wash your hand by saying it is not your job because your working in sales and you can't take the responsibility of service issue. After all the company paying you the salary so it is your responsibility to pay attention to this issue and negotiate with customer and help the company and customer to solve these kind of issues  

• Not face such situation but I like to add how shall be your response
• Speak gently and do not loose patient even in hard time
• Give best possible honest solution
• Keep calm and quite
• Refer to your superviser or speak out to superviser about issue

Always be fair, open, and trust worthy to your customer and communicate regularly and transparently then you can easily handle any situation of the customers.