Hopefully, you have AppleCare in effect on one of your Macs. If you do, then the Time Capsule is covered for up to three years from its original purchase date.
If you are not covered by AppleCare, it could not hurt to explain to Apple that the Time Capsule in effect is "new". Ask them very nicely to replace the Time Capsule for you, mentioning that you have probably spent thousands of dollars on other Apple gear.
If no luck, your only other option is to try to open up the Time Capsule and clean out the fan with compressed air to see if that helps. If you decide to do this, be extremely careful, as there are a number of connectors and ribbon cables that can be easily damaged if great care is not taken. A shop might be an option for repair, but the cost of this might exceed the cost of a new Time Capsule.
This link will provide some tips. The Time Capsule is the same device as an AirPort Extreme, but the Time Capsule includes a built in hard drive.
https://www.ifixit.com/Teardown/AirPort+Extreme+A1521+Teardown/15044