Matching ext of paint.

MY hood is at the body shop,the body man says he has a device that can match the paint,not sure whats its called and can i trust it.Have no choice,this goes back to WORST BODY JOB EVER REMEMBER IT.When it was time to tell the body man the paint coad,he got it.He however painted under the hood ,door jabs inside trunk,witch i did not want him to do ,I wanted it done at the same time at a shop that had a drown draft booth, not some back yard shop ,after the shop that had what I wanted painted the outside,it did not match was darker.I ask what coad they used they said what Bob gave us ya right,they gave me the left over,see there is the coad right on the can ,i got pissed and fought over this, I lost:wack: Bob work doing side jobs on at his shop, but work for the paint shop witch is well known so what is the chance my new shop will match. Sorry so long.