i have removed the terminals but cant work out what is holding the battery in still?

the backets on each side off the battery. its the same with audi a6. twist the bolts at the bottom of each corner

My audi A4 battery was held in by a clamp at the bottom. You possibly need an Allen key on a long socket to undo. Remember it was really difficult as it was in the bulkhead behind the engine. If yours is in a similar place get someone to help you lift, I nearly strained myself.

you can do this by calling a mechanic!!