OneDrive very important files lost and my case closed

I have a problem with very important files missing.

  Accidentally I deleted a desktop folder from my drive and it turned out, it is actually synchronised with my desktop.  The problem is that I couldn't restore all those files back which got deleted, I have managed to restore only around 40% only.  

After contacting technical support (Both Microsoft & One Drive)

They informed me files can not be found in their database and that probably I deleted them more than 30 days ago, of course it's not true. Once I started asking more difficult questions and requested some snip of my files history,  One Drive support closed my case with no further reply.

I am really not happy with this service.

I am wondering if there is any other potential solution to restore these files?