How to handle customer service scenarios when product defective and parts are not available?

First of all apologize for the defective product they purchased then assure the customer that you are willing to change it into a new one. Go beyond the extra mile. If the complaint was made through a phone call then ask if she/he wants to have the defected product be collected and change to a new one or if he/she wants to go directly to one of your service center. If she prefers the former then have someone to collect it from the customers address thru courier or shop personnel and bring the new product. It would be better if an expert sales personnel would go over the customer's place to change it and personally apologize for the mishap at the same time briefly discuss the new product benefits and advantages. You can also offer them freebies for the trouble caused. 

 I think customer service agents need to fix the situation but always start with apologizing to customer for the defective product they purchased then assure the customer that you are willing to change it into a new one. We have to give information to customer regarding the defective part. Then find out that part source of availability in our region. After that also part not available then will order that part in stoke and give assurance to customer. If the complaint was made through a phone call then ask if she/he wants to have the defected product be collected and change to a new one or if he/she wants to go directly to one of your service center. If she prefers the former then have someone to collect it from the customers address through courier or shop personnel and bring the new product. It would be better if an expert sales personnel would go over the customer's place to change it and personally apologize for the mishap at the same time briefly discuss the new product benefits and advantages.

First of all, we have to give information to customer regarding the defective part. Then find out that part source of availabilty in our region. After that also part not avaible then will order that part in VOR and give assurance to customer. Take him in confidence that same part will be replace shortly. and keep update him regarding the same.

I agree with Loraine, and focus & do anything to keeping your company reputation and reliability.