Why do bailiff companies answer complaints with a chronicle of the history of the debt?

It is to puff up the quantity of their response and make you give up your complaint.

Bailiff companies copy it straight from the case management system.

Sometimes, bailiff company employees use harsh, caustic and bitter language.

Only make a complaint to a bailiff company if you need to draw out their defence before starting legal proceedings. You can re-use their material against them later.

This is true if the bailiff does not answer your complaint, and substitutes it with a chronicle. You can given it in evidence because its shows the bailiff does not have a defence to your complaint.