New owner 2018 CR-V AWD Touring replacing rear differential fluid schedule?

Maybe it is getting use to this Maintenance Minder but it has yet to go off or signal me on anything. I took it in for it's last freebie oil change at 15,400 miles and they deemed that according to the maintenance schedule it was due for a rear differential fluid change at 16K so go ahead??? They wrote it down that I have it changed at 16K, 45K, 75K, and 105K OR EVERY 3 YRS, and so on. To the tune of $118.00. Said it was according to the maintenance schedule (which I have yet to find or so I can print out). Well I have looked at this BS Maintenance Minder Service Codes on page 142 in the owners guide and I see nothing about when to have that service. Call me old fashion, but I am use to a maintenance schedule that tells me to do this and that at this mileage interval and I follow it religiously because I average 800-1200 miles per week with my work, all of the mileage is 90% highway miles, averaging 70 mph. So I take care of my vehicles and generally buy new at the 250K+ mark with nothing but standard maintenance. They told me that my trans fluid should be changed every 3 years or at 30, 60, 90K and so on at the same kind of cost. :jawdrop: Now if they can take there "Quality Inspection Report" and write on it all of this info....where did they get that from so it could easily be printed off for me? I got blind sided by that huge charge for no more than a 15 minute job tops. Have done it before. Is there anyplace I can go to print off an actual maintenance service schedule? Now that I am up in age, 66, I have no place to do these changes myself and so I pay to have it done. Little help? Many thanks !!