Classic bank wire transfer. The only disadvantage of this option is, that the transfer may take 5-7 business days, depending on your bank. For the transfer, you’ll need the account number and other data of the service provider. Besides that, every time you’ll get a reference number, which you have to add to the “Additional information” gap. This reference code might be your username or a number, generated by the web site. You need to attach this number to make sure the service provider will know, to whom (which account) they have to release the required amount. On every site, you can find step-by-step guides for this payment option.