I just came off the phone with Bergsala.
Here in Denmark you need to send your Nintendo ID and the serialnumber on your new console to them in an email to service@bergsala.dk. If you have the serialnumber on your old console, then it'll be easier for them and it may be quicker if you call your support line. If you don't have the serial number on your old system, then they have to send your request to Sweden.
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Where do I find the serial number on my New Nintendo 3DS?
Either on the back (XL) or behind the