1994 Isuzu Trooper My car tend to Move to left side

1994 Isuzu Trooper Four Wheel Drive Manual

Hello
I'm justine salim from malaysia. First of all I would like to say sorry, because my english is not good. But hopefully you can understand.
Few months ago, I was accident. My car (isuzu trooper) was damage. The workshop try very hard to repair it. They try to fix the bent frame. After 2 months, my car is ready to drive. The problem is, my car tend to move to left side. I already check the car alignment and fix it, but my car still tend to move to the lif side.
The mechanic told me that, may be my car frame was twisted during the accident. So till now, I don't know what to do. Wheter to repair the frame, or to buy the used car frame? I also dont know where tu buy a used isuzu trooper frame.
I hope you can help me. Thanks