Xero generally do not allow us to apply promotional codes to the free conversions. They generally either pay for conversion of the data, or a discounted subscription, but not both.
At the moment until January 28 we can apply a promocode for a discounted subscription for MYOB New Zealand files. Email firstname.lastname@example.org for more information.
We can perform a conversion using the promo code for a cost of $330. This amount is in addition to any premium services. Email email@example.com for a link to this service.
Xero does allow to enter a promotion code in the Xero Organisation, through the subscriber settings.