I made a purchase by accident that I did not want. Can I get reimbursed. Order number...

You can try getting a refund on here xbox.com/refund

But how I can check other accounts history if I don't know what is the other account?

I have the order number.

Microsoft should be able to find an account related to this order number.

And I had a similar problem in the past with Origin.

I just had to make screenshots for them that I own all the DLC and by accident purchased them on two different accounts.

And they have moved all DLC to the account I wanted.

I completely forgot that I even had the second account.

Can you check in Xbox App if there is any other account linked there?

That's the only way I made the purchase in the first place.

Yes, I was checking the availability of a name I did want, Dankius, but with no numbers. The language the page used was so subtle it made it sound as though the numbers at the end wouldn't show up. But obviously that isn't the case. I was Blade XY7, and
now I've changed it by accident to Dankius3875, and I just want my old gamertag back, I want to cancel this change.

1.) I made the purchase on xbox.com

2.) I made the purchase January 25th

Order number: 7863575275

Did you get a reference number for the call you made to cancel your order.If you do have it MS can listen to the call you made and confirm the order was indeed cancelled.They would be obligated to refund your bank the purchase amount.