Essential Plan additional $15 on the 3rd line, and Autopay discount doesn't seemed to be applied

I'm confused by how essential plans are charged. Called the customer service but the lady just tried to get over with the call, so I'm posting question on here instead.

So I thought the plan is $90 for 3 lines (buy 2 lines & 3rd line free according to the attached screenshot), then plus the taxes & fees (about $15), the total should be something around $90 (3 lines) + $15 (taxes & fees) = $105.

But I got charged $120 each month instead. I looked at the billing details (see attached screenshot), looks like only 2 lines are included with the 3rd line charged extra $15.

So the total becomes: $90 (2 lines) + $15 (3rd line) + $15 (taxes & fees) = $120

So my questions are:

1. Is the 3rd line really free?
   • If it is free, then why is mine charged $15 extra?
   • If it is no free, then why is the web said such so?
2. In my billing detail, it also stated there is $15 Autopay discount, I don’t see that get discounted from my pay with Autopay setup already.
   • If the $90 (for Essential 2 lines) and $10 (3rd line) are the price after discount, then that means the below,
     • Essentials (2 lines): $90 after discount, original price is $100
     • 3rd line: $15 after discount, original price is $20
     • → Then the original price for Essential 2 lines is $100 instead of $90, which I don’t think this holds true with all the info I saw from the official website.

It’ll be greatly appreciated if someone could help clarify, thanks!

Here are the screenshots.