Gamepass Ultimate deal 3 months for $1

I had seen the promo that GamePass ultimate is only $1 for 3 months when I went and bought it, it only told me I had a month instead! I went to the website on Microsoft store and there were 2 plans one for 3 months and one for 1 month. I had spoken with
Microsoft support and they told me to come here and post the situation and give you guys the Case ticket number? I'm just confused because I have never bought ultimate in the past, and this was my first time having it, and It just made me concerned why I it
only paid for one month instead of the 3 months?

:)