If that is the case for you, I advice you to file a complaint with the Norwegian Financial Authority (Finanstilsynet).

SEPA is required by EU regulation to take maximum D+1.  If you make the transfer before your bank's cut-off time for the day, normally 14-ish, the money shall arrive no later than the day after.  In my experience SEPA transfers are often faster (hours) if your bank is a direct participant in the European interbank clearing system TARGET2.

Justcoin may spend a couple of days doing their own checks, of course.

Another protip: If you trade privately via SEPA, and the transfer takes longer than the expected D+1, it is probably fraud or phishing.  I reported two such cases to my bank upon reception of the money, before sending any bitcoins of course, and I was right both times.