Berlingo 2.0 HDi Dangel - problem

[RespiteCz]

Hello,

I want to buy a Citroen Berlingo M59 2.0 HDi Dangel 4x4, due to inspections at construction sites.
Now there is one advertised in our bazaar, but according to the seller, it has a defect that it starts, starts and doesn't go after a few meters. You need to grab the engine and start it again and it goes a few meters again. According to the dealer, the auxiliary transmission is bad. Don't know where the problem might be? Is it fixable?
Furthermore, the seller told me that it is a fixed four-wheeler, that it cannot be switched to a two-wheeler, is that right? Don't you know how much it can consume?

Thanks in advance.