I have not looked that the link, so I am guessing the subject here. I use similar places in the UK (very cheap to get an oil change and brakes etc).
What I do;
Mark the oil filter / spark plags whatever before you take it in.
Examine the "changed" components before you leave the premisis. Check the oil level. Look at the brake pads.
Give the car a good run on the way home to check anything else they have done.
If anything is wrong, politely point it out, and if they agree to change them do not make a fuss. I expect to get better service next time I go (there is not much choice around here, and they are loads cheaper than "proper" garages.