My 10 year Encore Azaleas are completely bare. First time ever. Also, first year I have used a lawn and shrub service to fertilize my shrubs. They also sprayed insecticide on them. Service began in May and now I discovered my Encores, which have been gorgeous, are now sticks. I have never had any issue before and my azaleas have been beautiful and occupy a large area around the back side of my house. It will be costly to replace, especially since they have 10 years of growth.
I don't know what could have happened to your azaleas, but something apparently has. I would start by discussing this with the landscape co. Also, take some samples of soil, roots, branches, and any dead leaves if you can find them, to the County Extension Service for analysis. This link will help you locate your local office: https://www.gardeningknowhow.com/extension-search/
If the landscape service is responsible, they should be glad to make right any damage they did. If you feel they are responsible and they won't admit to it, you should consult with a lawyer.