Google Play Store — Third party charges on my phone bill

I have almost $500.00 worth of third party charges on my phone bill for the last 2 months. Most of these charges were for "coin packs" that were almost $50.00 a transaction! I never received a receipt for this so how I was supposed to know that it was done and cancel the order within 15 minutes?? To make matters worse, when I went in to my account to dispute these charges and ask for a refund, I get an automated message back within minutes stating that it was denied and that the charge remained? Does my complaint not validate an investigation or hell even a human response? I know that I am definitely not the first person to complain about this and the resolution I am seeking is to have all of the coin charges removed from my account. I did not purchase these and I had no way of knowing that I was being charged for these until I received my phone bill.