Speedy Handle Replacement Cost

Sometimes I see preloved LV's that are in great condition aside from the vachetta. How do they make sure they get back in the original holes and not make the canvas more prone to cracking when they replace handles, and especially the piping etc? it seems like if the stitching was off even a bit it would make holes between the holes.
 
I have a Retiro PM which is in fab condition except for the handles which what ever I do can't get the dirt out. It bothers me as it was pre loved so was thinking of getting them replaced.

My issue is that the leather on the rest of the bag has a lovely patina and white handles would look silly. What would you do:

Replace the handles and try to darken them up and how would you do it.

Sell and put money towards another new one as cost may not be worth repairing.

Would love to know your thoughts.:graucho: