Xbox gold to ulimate help

Hello,

I converted my xbox live gold to ulimmate. I was told that it was 1:1 switching by a friend. My gold membership was going to end in December this year so i thought sure why not because I wanted to play some of the games in the Game Pass. However, I made the change and converted my gold to ulimate AND also purchased 3 months of Game Pass for £1 included which popped after mentioning converting via microsoft store. My membership said it's now going to renew in October which is £10.99? Meaning I got 1 month of Ulimate with my 6 months of gold and got 3 months of Ulimate for £1? Am i'm missing something or am i being silly haha.

Thank you , HED (Gamertag)

:)