Insurance paid claim without letting me know

Early this year I had an accident where my car rolled forward from stationary and kissed the back of someone's car and that person's car bumper was all wrecked when my car was completely fine (not even a single scratch was made)

I've taken pictures of that guy's car and showed them to a lot of people, they all said that the damage looks old and I couldn't have made such damage without any damage to my own car.

My car insurer sent an engineer to have a look and on the engineer's report, he said although the damage might be previously created but the fact that my car hit it had an impact on the damage as well, so my insurer paid the claim WITHOUT letting me know.

Now I have two questions:
1. What's the normal claim process? As in say if I was said to be at fault, my insurer should notify me and ask if I accept the decision right? And possibly an opportunity for me to contact the other person and see if we want to settle it privately between us?

2. My insurer has not kept me informed, and they paid in May, what can I do? Apart from just making a complaint, can I still get my NCB back since evidence really show that the damage was not done by me!

Any help/suggestion is appreciated! Thank you!