Target Prepaid Card Scam - DO NOT FALL FOR IT

I received a call from an unfamiliar phone number, so I let it go to voicemail. The voicemail said the 50% discount on my Xfinity account was about to expire within hours and I needed to call back today. That should've been a red flag because the discount on my account is not 50%. But I called the number back. It seemed like I was calling xfinity. Had the automated operator at the beginning listing options for customer service, waiting music, and then an actual person who was able to look up my actual account. He then went on to say I qualify for a promotion with target, in which my monthly bill would go down to $50 per month, but I had to pay the first 10 months up front, and then I'd be locked into that rate for 3 years. Sounds like a good idea, right? To make it more enticing, he told me if I opted in today, Xfinity would give me my next month of service for free. Even better! So I opted in. Received the usual email and text message saying my Comcast bill has been paid. I thought the next step would be me authorizing the $500 payment. Actually the next step was him giving me an authorization code and Xfinity billing number to call after making the payment. But the trick was the payment had to be made by opening a target credit card account or using two separate prepaid target cards. Red flag, red flag, red flag. I might've gone through with it, had I not done a quick google search and seen others suffering from the same scam and losing money. I did not go through with it, but I am extremely alarmed by how much information they had access to. How can my account information be more secure?? And did my account actually get credited for next month or did they somehow authorize a payment from my card that was already on file??? And what is comcast doing to stop this?? It seems like an inside job. I'm terrified just thinking about how much they have access to and how believable this scam was.