Are you sure you programmed it correctly? I've had no trouble with mine.
Not sure about the issue of hitting the switch, it going up and then going back down. Tailwagger shouldn't affect that, as that's a manual control.
One thing (back to the manual control), the Tailwagger cannot turn off the automatic features of the spoiler. For instance, say you have it set to go up at 50mph, but you drive above 90, and then slow down to 80. The spoiler will retract briefly, as that's the original control in the motor, and the tailwagger cannot shut that off.
If you deploy the spoiler before starting out, and speed up above 10mph, the spoiler light will come on and blink at 0-10 (it's a warning to let you know the spoiler is up at a slow speed), but will retract once you hit 10mph. These are all built into the spoiler motor itself.