While everything in lone wolfs reply is tech right and you should look for bad boots and bad afds etc...etc...old, lubrication, wear & tear, loose screws, boots, equal settings toe and heel....hard to see tiny DIN lines on the bindings ......
go to http://www.dinsetting.com/ fill in your info and see if the result agrees with what your shop put in for u.... it is like using a chart but it figure it out for you.....and is similar enough for bindings other than Salomon and Marker...
The only choice u get is Skier type. Yur choice, your responsibility. These charts were made whe skiing was on snow - not on rails, or big air or from cliffs.
So the question u ask yourself - do u need retention or release ?
Would u be better off in your crashes if the ski comes off ? or would you be better off if the ski stays on ? Racers crank em up to like Din 22 or higher. They are F! if their skis come off at 140 km / hr. and they get a small chance to try to recover or ski it out it the ski stays on. They need retention.
Recreational skiers on snow usually need release. They are better off if the ski comes off.
The way u know ur DIN is set too hi is when ur broken leg is still in the binding. Up until then u think ur DIN is too low..