2003 Audi a4 quattro 3.0 won't crank

I've had my 2003 Audi A4 Quattro 3.0 for
about 6 months now and it has been in the
shop for about 6 months now the first few
days I had it it was fine and then it started
not wanting to crank then after that is
started not crank it at all and took it to the
mechanic shop they said the timing was off
I got that changed then it still wouldn't crank
and I got the fuel pump changed still
wouldn't crank get the ignition switch
changed that didn't work also replace the
spark plugs wires and coil pack still isn't
cranking what else could it be? Also change
the relay switch