Knowingly register a Pvt Ltd company name which we already using

Dear all, Due to some reasons i'm not using my company name. I'll mention XYZ on behalf of my company name. We are based in Chennai, Tamil Nadu. We run a business in Chennai for almost 6 years. Its a IT training services. Me and my friend runs the business. Initially we got advised to go with "Partnership Firm" registration as we are not fully understand /prepared for "Pvt Ltd" registration. So, we registered with "Government of Tamil Nadu Registration Department" - "Form C". And got acknowledgment on 2013 form district registrar of firms, Chennai South. Everything goes fine until mid 2016. We've planned to expand our services to "Bangalore" and that time my brother [relative] seems very much interested to promote our brand as a franchisee. Later things are not moving into the expected direction between us, he left us by saying "I don't want your company name. I can go alone from here.". We indirectly lost almost 2Cr of revenue in that year [mid 2016 - mid 2017]. Nothing was signed as an agreement from starting to end. We blindly had trust and waited for 1 year to get some franchisee fees and move on. Later we decided to open a new branch in another location which is around 12kms from his place. At that time we clearly told we are ready to sign agreement which will be safe for everyone. But he rejected. And one fine day we got to know he applied for a trademark which we used for all marketing purpose [a different name, not our company name]. Even at that point we insisted him to surrender all those trademarks to us in polite way. We got negative answer. And he told us finally "I can go alone without your company name from here". Note, the final decision which was taken by him. Not by us. He is still using that name which we used for marketing all the way around 2 years. After 2 months time-frame we decided to open a new branch in the area of where he is running his business. And we opened our office by july 2017 which is slightly 200mts from his building. Now, he called me and mentioned he is not happy with this location. I told him, "We don't have anything in between us. No franchisee. No agreements. Even, you left us. not we left you. Any one can run a business at anywhere. Lets do the business peacefully" Now the problem is he registered a pvt ltd company name which we registered as partnership firm before. I'm not sure, what way we can handle this issue. Needed experts help. PS: We applied for trademark for our company name 3 months back which is accepted and advertised in journal. But we didn't get any certificates from trademark registry. It will take around 6months to issue certificate as we read somewhere in internet.