How can I be certain purchases did go to my XBOX

You can check your purchase history here https://account.microsoft.com/billing/orders/

It will display any purchases on your account. If you do not recognise a purchase, then you can challenge it. If you are seeing payments on you bank/credit card account that do not tie up with your purchase history, then contact your bank/credit provider
and state that these are fraudulent.

Yes thanks I have done that but is that 100% accurate? It cant be manipualted?

You can track your transactions at http://commerce.microsoft.com however, it'll only go back a certain amount of time so it may not show everything you've purchased.

I can only see this -

Points purchase AU $30.00

Completed.

I see a date, my billing details and order number. But no details of how many points or where and what points were exchanged for.

Thanks, I can see my order history on my Xbox says that the purchase did go through and is pending but it does not show this in the link.