Well it's your lucky day
The belt size for the alternator/water pump is 10x850 where 10 is the width (in mm)
and the 850 is the circumference of the belt (also in mm).
The followong aftermarket belts are applicable:
Bosch AVX 10x850, Bosch order number: 1 987 947 606
Gates AVX 10x850La
Before you try to rearrange the pulleys I recommend to install
the new belt (to crankshaft inner pulley, alternator pulley and
water pump pulley). After tensioning the new belt you will see the
pulleys are in line or not.
I think the person who installed the A/C wasn't wasted time to
align the waterpump or the alternator pulley axially by using spacer(s).
Removing the crankshaft pulley is a little bit painful.
The main steps:
Remove the front grille, drain the coolant, and remove the radiator
to access to the nut in the center of the crankshaft pulley.
Remove the A/C and the alternator belts.
You will need a 36mm socket and an impact wrench.
If impact wrench is not available, a torque wrench will do,
but in this case an another special tool is needed to prevent
the flywheel (and the crankshaft) from turning.
When using torque wrench I recommend to
remove the hood too. After removing the nut the crankshaft pulley
can be pulled off from the end of the crankshaft.
When reassembling I recommend to use some threadlocking adhesive.
Tightening torque for the nut is between 145-165 Nm.
I would love to help you in person, but i'm 8000 km away...