From my recent experience my hosting site was not able to help me either. What I found was after I did a DANTE update something happened to the first line of the htaccess file. The first line couple of lines on the htaccess file were all placed together and not on separate lines. I just placed the items on their correct lines and it fixed the error. You should be able to access this via your Cpanel.
I know the 500 Internal Server Error is a general error so this might not fix your problem like it did mine. Might deserve a look.