Under henvisning til mangelen ber forbrukeren om omlevering.

It is a formal fixed expression. In this kind of legal or administrative Norwegian, under henvisning til means something like:

• with reference to
• referring to
• on the basis of

So the phrase introduces the reason or basis for the request.

A learner should note that this is not especially conversational. In everyday Norwegian, people would more often say something simpler, such as:

• på grunn av mangelen
• på grunn av feilen

This is because Norwegian follows the V2 rule in main clauses: the finite verb must come in the second position.

The sentence starts with the fronted phrase:

• Under henvisning til mangelen

Because that phrase is placed first, the verb must come next:

• ber

And then the subject follows:

• forbrukeren

So the structure is:

• Under henvisning til mangelen | ber | forbrukeren | om omlevering

If you put the subject first, you would get:

• Forbrukeren ber om omlevering under henvisning til mangelen.

That is also grammatical.

The verb is å be om, which means to ask for or to request.

Here:

• ber = present tense of å be
• om = the preposition that belongs with this meaning

So:

• ber om omlevering = requests replacement

This is very common in Norwegian:

• be om hjelp = ask for help
• be om penger = ask for money
• be om reparasjon = ask for repair

Without om, be usually has a different structure or meaning.

Because they mean the consumer and the defect.

In Norwegian, the definite article is usually attached to the noun as an ending:

• forbruker = consumer

• forbrukeren = the consumer

• mangel = defect / deficiency / lack
• mangelen = the defect

In legal Norwegian, the definite singular is often used in a generic legal sense. So forbrukeren may not mean one specific consumer in a story; it can mean the consumer as the legal party.

The same applies to mangelen: it refers to the defect at issue.

Not quite.

• mangel is a formal/legal word often used for a defect, deficiency, or lack of conformity
• feil is a more general everyday word meaning fault, error, or problem

In consumer law, mangel is the standard term because it is more precise. A product can have en mangel in the legal sense even if an everyday speaker might simply call it en feil.

So in this sentence, mangelen sounds specifically like the legally relevant defect.

Omlevering is a formal consumer-law term. It refers to a remedy where the seller provides a replacement item instead of repairing the defective one.

So it is not just any kind of delivery. In this context it means something like:

• replacement
• replacement delivery
• getting a new equivalent item

It is much more formal than everyday expressions like:

• få en ny vare
• bytte varen

A native speaker would understand omlevering, but it sounds especially at home in contracts, complaint letters, and legal texts.

Yes, it is completely correct.

There are two different things here:

• the first om is the preposition in be om
• omlevering is a noun

So this is not repetition by mistake. It is just an accidental meeting of similar forms:

• ber om
  • omlevering

Norwegian allows this without any problem.

Because omlevering is being used as an uncountable/legal remedy noun here.

After verbs like be om, Norwegian often uses the noun without an article when talking about a type of action or remedy:

• be om reparasjon
• be om refusjon
• be om erstatning
• be om omlevering

This is similar to using abstract nouns in English without a/an in certain formal contexts.

If you added an article, it would usually sound less idiomatic or change the nuance.

Yes, very formal.

Several things make it sound legal or administrative:

• under henvisning til
• mangelen
• forbrukeren
• omlevering

In ordinary conversation, a speaker would probably use something simpler, for example:

• På grunn av feilen vil kunden ha en ny vare.
• Kunden ber om å få en ny vare på grunn av feilen.

So the original sentence is good Norwegian, but it belongs especially to consumer law, formal complaints, or official writing.

Yes. The original sentence uses a formal fronted phrase first. A more neutral order would be:

• Forbrukeren ber om omlevering under henvisning til mangelen.

That keeps the same meaning but feels a bit more straightforward.

If you wanted something more everyday, you would usually also change the vocabulary, not just the word order. For example:

• Kunden ber om en ny vare på grunn av feilen.

So there are really two separate issues:

• word order
• level of formality