diagnostic rip-off

In February my 2016 Silverado's battery shorted out started a waterfall effect with tech services. The dealership fixed my truck, I got it back after numerous repairs I received my monthly diagnostics by e-mail from OnStar and it stated my truck had a problem with the starting system in my truck and service is needed immediately. Took it back to my dealership nothing wrong so-called OnStar thru the truck ran a diagnostic and said no codes found. Talked to tech support and said would take care of issue, next month got same e-mail with the same problems listed went thru same scenario same results this went on all spring and summer finally I contacted tech support in August and told them either fix this issue or I will cancel it altogether. Was contacted 2 days later they said problem was solved I will have no more issues on my e-mail diagnostics. Fast forward to October 1 my son took my truck on a fishing trip some 200 miles away. He called me at 7am said the truck is missing and the dash looks like a Christmas tree what do I want him to do I said to call OnStar and ask for a diagnostic report and then I got an e-mail from OnStar saying thank you for enrolling in OnStar diagnostics so the way they fixed my issue was by turning my diagnostic service off and didn't say a word and kept paying the same amount. To me this is a major rip-off I am going to contact better business bureau and see if anything can be done for these people taking advantage of unsuspecting people.