I work in Handbrake House and I get them reasonably often. As has been said before, there is a standard form we send back where we fill in the detail from JPA, unless the mortgage company is asking something weird, in which case I'd phone you and ask you what you wanted me to put down.
It's quicker than SPVA/OC Admin/BSW etc and you can have some input into what you want me to send back.