A6 Avant defective/damaged rear door lock

[Enyamp]

Hi All

I wondered if anyone had any advice on a problem I'm experiencing. A couple of months ago, the rear door on my A6 Avant wouldn't open for a couple of days. Now it won't seem to shut properly.

Has anyone esle experienced this? I'm going to have to take it in for repair as I can't have a car that won't lock, but it would be great if I could identify what this might be and/or by the part myself to keep costs down.

Any help/advice really appreciated on this.

Thanks!