2 payment methods in one transaction

It should just automaticlly ask you if you want to pay the remaining balance using the credit/debit card linked to your account if you don't have enough currency in your Microsoft account.

The transaction may be cancelled due to one of the next reasons:

1. Your payment method is not physically billed and issued in the Xbox store region that you're trying to use

2. Your bank is rejecting the payment method

3. The information of the payment method used is not completely correct (billing address doesn't match with the card info - the card info itself is not correct)

Hello,

You wouldn't be able to remove the payment method due to their being a pending transaction associated with that payment method. If you wish to remove this payment method you'd need to contact Microsoft Store support first and cancel your preorder so the pending
transaction is released on the account.

If this payment method is also attached to your Xbox LIVE Gold subscription you'd need to turn off automatic renewal and wait for that subscription to end before you're able to take the card off of the account.

Yes, you can. You will need to start the transaction with a payment method (credit/debit card). You'll be prompted after doing so if you'd like to use your Microsoft Account balance on the transaction. It will empty out your Microsoft Account balance and
charge whatever the remainder is plus tax to your payment method.

it is best to buy bigger amounts then multiple small amounts in a short period if you want to avoid transactions locks

its usually 2 transactions per day but it has to be spaced out reasonably like 1hour per transaction

this is a anti fraud trigger

or you can wait 24hours before you can use the same payment method again