It's not unusual to find someone in the work place who tries to always find an excuse for not doing his tasks. I was not spared with those types of work place confrontations.
I was working then as an Electrical Maintenance supervisor. Before leaving the shop floor in the afternoon, I already have a list of tasks for each electricians on the board as the first shift is coming in 6:00 AM and I usually come to work at 8:00 AM. I don't want my electricians to be waiting for me for them to know what's up for the day. Regular tasks such as production support and shop equipment repairs were not so problematic. Usually, the personnel rotation for these were on a weekly basis thus when an electrician arrives, he already know what's up for him for the day.
One of my electricians got a BS Electrical Engineering degree. He already passed his Assistant Electrical Engineer licence. But being a newbie and does not actually know yet what is the difference between a theory and practical application, he accepted the role of an electrician to be able to explore the trade.
As a start, I have assigned him on the shop floor helping on the repair of motors. He is a bit annoying to the lead electrician and I always receive complains about him. Since it was summer time, the ambient temperature was higher than what it is meant to be, the substations were overheating. A sign of these was the frequent failure of the air circuit breaker slider contact. There were several causes of this fault though, a loose contact, a mis-aligned installation, overloading, high temperature and many more. By process of elimination, the high temperature was the culprit.
The substations have a cooling system using forced air extraction and incoming ambient air was water-cooled. Since we have not been experiencing the ambient temperatures as high as this, the cooling system were actually not maintained. The water pipe line were already corroded and not replaced. Manual filling is required.
I have assigned this guy to oversee that the water storage level. The temperature was actually high as the water on the cooling system evaporates very fast, it only takes about a day or two.
The following week, I got a visit from him saying "I can't continue doing my task anymore!", I asked "Why?". He replied, "we should have the water pipeline repaired. I said, I already made a request for that, but we can't just leave the substation overheating while we are waiting for the pipe fitter to complete the line.
Meantime, I bought him a garden hose for the purpose. I still get complains. I have given him a reliever, I still get complaints. Not until the pipe repair was finished that he kept on complaining, always have that alibis in order for him to not do what his assigned task is.
Workers complain because they feel that they are not suitable for the task or they deserved better. If this is the case, give them what they want if reasonable. If you still get complaints, then that will be a different story.