We had a client who requested that we troubleshoot an electrical problem at their store because they had about 20 lights out. We sent an electrician who said that they needed to order at least 20 lamps and possibly a few ballasts. This particular client orders their own lamps and ships directly to the store. They wanted to know how many ballasts were out so they could go ahead and order them as well. We were unable to find out if the ballasts were actually out without first replacing the lamps in the fixtures, so we could not give them that information.  This was frustrating because they would then have to pay for a secondary service call. The store went ahead and ordered and replaced all the lamps in the fixtures, but they had about 15 lamps that were still out. The client requested that we send a technician back out and stated that they should not have to pay for a secondary service call because, in their opinion, this should have been taken care of the first time we were out. We sent another technician to the site and I requested that they test every single fixture to find out the issue.  The technician went to the site and tested each fixture with the correct lamp and found the reason the lamps kept going out was that the store had ordered the wrong lamps. I advised our client of this and also provided them with the specs to order the correct lamps. They apologized and advised that they would pay for the secondary service call to complete troubleshooting. We did not charge our client for the secondary call as a matter of principle. But they recognized that we had gone above and beyond and thanked us for our added effort to figure out the issue.