Dear Sir or Madam,
I am writing with regard to the malfunctioning modem that I purchased from your shop on 
last
 week.
The modem performance was good in the Linking Words
first
 2 days after installing but from the 3rd day, I feel a signalling problem. When I was Linking Words
in
 a video call that I need to do frequently while working from home, I found Change preposition
on
sudden
 disconnection from the internet. Correct article usage
a sudden
Firstly
, I called my internet service provider to check their line, but after the checks, they confirmed it is for modem signal fluctuation.    
As I am engaged with different projects all around the world, it is mandatory for me to be online most of the time and respond to different technical queries promptly. Linking Words
This
 sort of problem, not only wasting efficiency, but Linking Words
also
 harming with a financial loss, and which is sorely disappointed.
Linking Words
This
 product has 6 months replacement warranty period, so I want to replace it immediately. What you need to do to send the new product without any delays. 
I trust you will act quickly as so as you received the letter.
Yours faithfully,
MazharLinking Words