So, i signed up for a new rust server using ServerBlend and in their command-line setting it asks for map seed and map size. So I put in map seed of 0 which generates me a new random map when i started the server.

But now whenever I wipe the server it still uses the same old map seed even tho I have Map Seed set to 0 still. Is there something I'm missing?

You need to ask ServerBlend since they are the ones providing the tool that sets the seed.

When you set the seed number it will continue to use that map until you change it. the map itself might change a little with the changes in the game, But to take 5 minutes each month  to find a map to use is not that much trouble is it ?
I look for a new map (from RustIO) that is considerably different to the existing one (each month) and change the seed.
I server host gives you FTP access so that you can make the choices ,