Sir sanding of brake pads is a joke to earn labour. The minute you apply brakes after this process you are back to the same situation as before it. I don’t get why rubbing a layer off with sandpaper is necessary because the brake pad is constantly grinding and rubbing itself each time you apply brakes 
I am at 31k mileage and get my car maintainence from 2S although my car is now almost 3.5 years old. Never got this brake pad sanding done. Although getting calipers greased every 20k is suggested
Even if you only get oil and filters changed without anything else done they are bound to stamp service book. If you want to get rid of 3S or 2S service there is no harm in doing that. Just use genuine filters and parts and also get your service book filled every 5000 even from a private workshop so you have record.
