Case Update: After troubleshooting with Dell-Cares, Dell replaced the keyboard and mouse under warranty. 
Can anybody share what is the process to claim warranty for KM117 keyboard and mouse combo because on dell site for warranty it first asks for a service tag but the product has no service tag given and any other number given with keyboard or mouse is not accepted by the site. Also there are no contact numbers or mail ids where we can share the issue. I also tried calling the customer care and connect with the warranty dept and had the worse experience. First they pretended to not hear me even when i could hear them perfectly and had good network on my side and laughably tried to avoid answering me, and in subsequent tries they simply disconnected the calls without answering. How can one claim warranty for a product if both site and customer support is unavailable for the product?
Warranty Claim for Dell KM117 wireless keyboard and mouse combo