It could be the "ACT" working - Anti Crash Technology... I trained a couple guys on this and it does just what you mentioned...

If you "hold" a control too long, it sets everything back to zero (usually) and is designed to let the airplane stabilize itself in flight... Yours may be giving you oposite control because the plane is not sensing correction (I'm pretty sure that plane has the light/dark sensor)...

So, give everything a look over as suggested.

Try the controls with the ACT turned off (on the ground)..

Then, if possible, have an experienced pilot test the plane..

Good Luck... It's a pretty darn nice little plane, a couple of incidents should not have done it in..