We have a global website example.com and also and Indian website example.in. But recently we found that the domain name example.co.in has been bought by my competitor and is being used as a mirror website for their own website. This could lead to confusion to our customers. I have emailed them asking them to bring the website down, and I am still waiting for a reply. What could be the best solution for such a situation.
If you have an established trademark, then you could file a lawsuit against them. If it is a generic name, then there isn't much you can do. It probably not worth the expense to go after a .co when you own the .com.
Now cyber crime is on the rise, you should have thought of something like this in advance. If you have protected your rights then you can file a lawsuit against them.
Mjewel may be right, but you have to check the laws in India. In some countries a domain name is covered under trademark law (which would mean that your competitor is guilty of trademark infringement).
It might be worth it to make a small note on your website, letting customers know that your are the "official" domain for your business. Other than that, unless you have a strong brand you can leverage I wouldn't spend the money to fight them legally. If your established and a unique brand name, go after them and shut them down. Might also be able to report them for Google, maybe they have heavy link manipulation or other spammy techniques you could get them de-indexed for?