I can sympathise with your frustration. My S-TEC went do-lally and scared the crap out of me. The yoke suddenly sent the ailerons into full deflection and the aircraft rolled inverted. I was reciting my VFR essay to ATC when it happened - I bet they periodically re-run their tapes to enjoy the plethora of non-CAP413 utterances I was screaming as I was showered with pencils, dried mud a checklist and an iPad.
After a thankfully relatively inexpensive repair I was told that the connection to the turn coordinator had apparently fallen off (or something like that I think). The autopilot would have cheerfully barrel rolled me all the way home at constant altitude (worth watching from the ground I'm sure).
I am now much more phlegmatic about the autopilot and my hand is never far away from the disengage switch. Interestingly, despite some initial training from my CFO and regular use, I can confess that I did wrestle unsuccessfully with the yoke for a full second before I had the wherewithal to push the disengage button.