If the order has already been paid by credit card or PayPal, no changes can be made.
If you have chosen Bank Transfer or Financing, you can request to change the payment method by writing to info@tecnomodel-treni.it.
However, you must have saved a credit card or PayPal account in the "My Payments" section to be able to make an automatic charge.
Otherwise, you will have to request cancellation of the order and place another order choosing the correct payment method.