I recently had my truck oil change with Lube World, During an inspection of all the truck fluids I was informed that my rear axle differential fluid needed replacing, I said that it had been done May of this year, but according to the mechanic from lube world it has not been changed for a year or two. He could tell my the colour of the fluid it was black and not transluence as it is suppose to be. There fore my complaint is Maple Ridge Chrysler have charged for a service they said they have done (on paper) but not actually carried out

What can I do next?