Service invoice in NAV 2013 R2 - no unit code

Hi,

We have a new installation, where we want to use the service module. We have set most of it up, but have a couple of issues:

When we add a service item or a normal item to the service contract we have a unit code on the service contract lines. However when we create a service invoice the unit code is empty on the service invoice lines. We cannot enter the unit code manually, because service transaction lines are created. How do we get the unit code to be copied to the service invoice lines from the service contract to the service?
Because we need to create an OIOXML file from the invoice, the unit codes must be used.

On our service contracts we will typically have a number of lines. How do we set up, so we on have one total price line created on the service invoice? We want the invoice to look like this:
Txt from contract line one
Txt from contract line two
Service total priceā€¦

Thank you.