want to cancel a transaction

You have two options here:

1. Log in to this link https://account.microsoft.com/services to turn off auto renewal

2. Call phone support and ask them to turn off auto renewal (best method). You can get the number for your region via this link http://bit.ly/2ee23wg

But I don't want the refund, I want the gift card to be processed, it seems as though the system is cancelling the transaction by itself

Sorry can't cancel it in here you will have to cancel it either by login to your Microsoft account and cancel go to bills and payments or recent transactions usually gives you option to cancel.

Hi there,

for any billing issues or refund requests you will need to contact Xbox Support (By Phone or Microsoft Support Chat) They are the only ones that can determine if a refund is in order or not.

To contact them use
support.xbox.com/contact-us Be aware that the options shown are based on the issue selected.

ummm that's because they are final transactions

You can't just click buy

It. Takes two clicks

And with all online transactions they are labelled as final I'm not sure where you would get the idea there is a cancellation button other then cancel the download progress because it would be the first ever