Non-receipt of gratuity after 12 years of service due to technical resignation

It is kindly submitted that I Ex-employee VIKRAMADITHYA.V, of CRPF now Officer in GAIL India (Central Government PSU). I joined CRPF on 01-07-2005, in 2017after obtaining NOC from CRPF, i appeared for selection in GAIL and after selection in GAIL, my Technical Resignation was accepted. I resigned CRPF w.e.f 21/11/2017(AN), i requested receipt of gratuity or transfer of gratuity to present CPSU but it was rejected by CRPF by following exact reply i;e “payment of gratuity to a person retiring before 10 years of service is to be made but in the present case since you have merged with another department and not retired hence you are not eligible for Gratuity from this department” It is requested to advise me whether am I eligible for the Gratuity benefits for my 12 years 04 months and 20 days CRPF service, if eligible then what to do next.