Cenrtral locking mystery

[Guest]

I have a 2010 A3 1.6tdi.......great car but have a problem.

 

Remote locking key no 2 has new battery and light flashes but nothing happening on car.

Key no 1 was working normally but suddenly stopped working.

Light on key flashes and lights on car flash with noise as if locking is trying to work.

Only front door locks or unlocks using either key manually.So I cant secure the car other than front door.

I know that I may need 2 new keys...they do give up, but why the problem  manually locking/unlocking with keys???

Cant use the car without being able to secure it so need urgent solution...anyone any ideas??