It is really good if you do some courses. Since you are interested in PGDHRM from Symbiosis through distance learning, initially, it will be hard to take a break for your career. As you are already working, you will experience some change. Don't worry about the pay difference at the beginning. My advice is to pursue the course. If interested, continue there as an Admin/HR Exec if an opportunity is provided; otherwise, consider changing to a relevant job to gain exposure. Then, aim for a better salary. Once you get the right breakthrough, the salary will not be a constraint. The important thing is to get a breakthrough in a relevant job
SAP will be helpful if you are a Professional Graduate. It is not advisable for BSc graduates. You can pursue it later after completing PGDHRM and gaining at least 2 years of experience
Cheers