CS777 (w/ Salty Compatiblity) Uncontrollable Trim When Climbing

Hello Everyone

So when climbing to cruise alt i noticed the plane would not “climb properly” as the V/S was going up and down repeatedly, i then noticed that the trim was set to full nose up by itself, i disabled the A/P and still wasn’t able to control the trim or set it to neutral and the plane then stalled by itself despite my efforts…

Any kind of help or explanation would be much appreciated as it’s not my first time experiencing this…
thanks in advance

(Just to get one thing clear before i get any message on it, i know i was dumb buying this plane, and the plane is crap)