ok, I, like many don't know much on this, but want to avoid various things.

Have the A6 C6 3.0tdi S Line Quatro (Engine code BMK)
Have the leaking injector issue.
Can make out the injectors are 0445115 which I am led to believe are the Piezo injectors and thus cannot be repaired.
I have been told to be careful when getting used ones, there are many copies (chinese) that are not good, and many that say they are re-conditioned but can and likely will cause further issues.

So, the questions.

1. if I have Piezo, and they are leaking, can I replace them with re-conditioned non Piezo Injectors, which may be cheaper and in the long run better?
2. If I have the injectors tested will the test reveal the leaks?
3. if the test does reveal the leaks, and only 2 are leaking, presumably it is ok to just replace those 2, then maybe in a couple of months get another 2 replaced and so on?

All I was able to get from my injectors was the following

059130...
041123
AB5BCMUD....
0445115

Thanks and sorry if any of this has been covered before.