The culprits responsible for subscribing your account to theses Value Added Services are the ads or pop ups from the websites you visit. A lot of websites nowadays use ads for revenue. Some of these ads are very malicious, some would subscribe you to a VAS without your consent.
You may call 211 and request for an op-out from all the VAS and reversal of the charges. I had this problem before and I was able to resolve the issue pretty easily just by calling their hotline.