Resolving WiFi interference 2.4GHz/5GHz Set-up:
iPad user connects to WiFi via Airport Express. A printer is attached to Airport Express for (Airprint) printing facility.

Problem:
I am using the above set-up with the permission of IT (I am an external staff person who is not on their payroll). Recently IT has reached out to me saying that I need to remove my Airport Express because it is causing  interference to their devices and making them slow. Since Airport express broadcasts both on 2.4GHz and 5GHz, I was thinking as a possible solution I configure Airport Express to 5GHz only (less crowded spectrum). I think there is no possibility to restrict Airport Express to broadcast 5GHz network only (it will broadcast both 2.4GHz &amp; 5GHz) therefore I was thinking to get a good value router/WiFi base station which has the capability broadcast only 5Ghz WiFi. I have looked up on internet and couldn't find any good value router which could serve the above purpose. My questions are 

1) Will the above proposed solution (5GHz network only) could resolve my interference woes? 

2) Please suggest an alternative (with specs) to Airport Express which could be roughly of same value and has the printer attachment capability and could broadcast 5GHz WiFi only.

Caveat: I have already scanned the WiFi Spectrum 2.4GHz is very crowded therefore changing the channel wouldn't resolve it plus frequencies are overlapping, 5GHz spectrum is less crowded (only 1 more SSID other than mine is residing there, hence I want to broadcast only 5GHz radio frequency so that IT doesn't blame me that my device is interfering/crowding their 2.4 GHz spectrum) 

Thank you!
There is an app, WiFi Explorer, which shows all the networks your computer can see. It also shows the relative strengths and channel number of them. You could use this to determine that the problem is indeed 5 GHz. Maybe changing Airport channel will help. The app is not free and is available from the App Store.