Pre-owned vehicle issues

I purchased a vehicle from Lenasia VW, a pre-owned vehicle, after a month of having the car it started having issues to which I took it to Toyota to be fixed multiple times with no resolution, car was still under Toyota warranty but still couldn't get fixed. I did let the dealership of which I purchased about the issue but all they could say is that it's not their problem anymore and can't find a common resolution about it. The warranty company says they can't pay to fix the issue as it happened before I even took the extended warranty with them.