First, confirm the DAU and the SIU in the aircraft, not all units belong to Radiant Power.

Radiant Power does not support the DAU in the PA46-500TP. Avidyne is not aware of any shop or company that supports the DAU (or the mini-DAU) from this aircraft.

If the aircraft (Piper PA28, PA32, PA44) has the A1215, Avidyne is not aware of any shop of company that supports this DAU. 

Issues with the Radiant Power supported DAU's and SIU's are redirected to Radiant Power in Sarasota, Florida (USA):

Radiant Power (DAU & SIU) Repairs
7135 16th St E #101, Sarasota, FL 34243
(941) 739-3200 

7:30 AM - 4:30 PM Monday - Thursday Closed on Fridays