If they used any kind of cleaner with ammonia (regular Windex uses ammonia), this will damage the finish on most any outdoor TV screen. Regardless of the manufacture.

It is simple carelessness by the cleaning people. Not learning their job and what chemicals to use for what application. Sorry for the customer but if he wants it fixed = new TV. The cost of the screen & labor will probably be almost 1/2 the cost of just getting another one. And you probably will have trouble sourcing the screen.
Personally if I were the customer, I would go after the cleaning crew for compensation. That's what insurance is for and they will learn a lesson about doing their job correctly.