Why is Showtime currently advertised at $5.50 for three months but that's noth the price on my account oage?

Direct TV Stream is advertising Showtime at $5.50 for three months, but when I go to my account online, it say's Showtime is $11. per month. Nothing about the advertised price on TV. I just called Customer Service and was told that offer doesn't apply to me because I've had Direct TV Stream for so long. There is nothing I've seen on the commercial that says you have to be a new customer with Direct TV Stream to get the Showtime offer of $5.50 for three months.

Sound to me like false advertising!!