Tenant complained about damages after repair

[Elena Koyun]

We have installed a new window in our tenant's apartment. Tenant sent us the following email "We would like to address an incident resulting from the window installation. We noticed today that some of our property was damaged I have attached pictures. One of the figurines that was on top of our wedding cake made by a friend has been permanently damaged and I don't think it could be fixed. We were not notified of the damages. The workers left a bunch of metal and screws on our bookshelf as well as a bunch of dust and some of it was placed directly on one of our wooden pictures. Another thing that is concerning to us is our camera was unplugged while they were working. I understand if this needs to be dealt with after the holidays. I just wanted to touch base before I forgot."

This is the first time for us please advise what to do and how to respond? We did notify them that we will have people coming to install a new window way in advance and a day before the event. Yes, we assumed that they would move stuff away from the window but looks like they didn't. 

We appreciate all the suggestions! Thank you!