reducing camber increased toe in, why?

[omodos]

LOOOOONG story, but here it goes, wanted to reduce negative camber at rear of my e53 3.0d sport package, garage could do this fine but as they reduced the camber I started getting toe in( wheel started to point inwards ).....and garage told best to leave it with more -ve camber rather than the toe in....any ideas why, have i got bent components causing this issue?or would worn components cause it?same on both sides but moreso on one side....