There are many institutions in our country where one can get admission for doing part time PhD in marketing topics. The minimum eligibility is full time Post Graduation degree with at least 55% marks (some institute insist for 60%) in Economics / Commerce / Psychology / Sociology / Public Administration / Statistics/ Mathematics or full time professional qualification like CFA / CA / CWA / CS with at least 60% marks. The selection would be through an entrance exam for a particular institution or a centralised exam for a group of institutions. The entrance exam is generally followed by a group discussion and personal interview. The duration of PhD work is generally 3 years. Some institutions take the candidates just based on the merit as per the marks obtained in the qualifying exam. You are already working in the marketing area so doing PhD in your core area is a good thing for progressing in your career.
Some of the colleges where one can try to get admission for the part time PhD program in marketing are -
1. Indus University, Ahmedabad.
2. Indian Institute of Management, Bengaluru, Karnataka.
3. Gian Jyoti Institute of Management and Technology, Mohali, Punjab.
4. Delhi School of Management, Delhi.
5. Indian Institute of Foreign Trade, Kolkata, West Bengal.
6. Parul University, Vadodara, Gujarat.
7. Amity University, Mumbai, Maharastra.
8. JSS Science and Technology University, Mysore, Karnataka.
9. Alliance University, Bangalore, Karnataka.
10. Vinayaka Missions University, Salem, Tamil Nadu.
11. Loyola Institute of Business Administration, Chennai, Tamil Nadu.
12. IILM University, Gurgaon, Haryana.
After doing PhD there are many scopes in the industry and some of the positions where one can apply are Marketing executive, Marketing manager or Product manager. There are plenty of areas where marketing people are required and some of them are manufacturing, wholesale trade, retail trade, professional marketing services etc. As you are already working so for you switching over would be a bit easier as you are aware of the basic marketing areas.
Knowledge is power.