Google Play Charged Me for Purchases I Didn’t Approve

I just found out that others bought things using my Google Play account without my permission or knowledge. I asked for a refund right away, and I've done it more than occasions, but I haven't gotten a clear answer or explanation. When I check the status of my refund, it's either ignored or automatically turned down without any explanation. I still don't get why I have to pay for something I didn't agree to and certainly didn't want. It's frustrating to not be able to regulate my own account or spending, and it's even worse when I can't get help from a real person. I never believed that a service like Google would leave customers so powerless when they saw charges that aren't theirs.