The blockdata command for shrinking the tardis just comes up with the result of the targeted block is not a data holder

For reference, an issue like this would be better posted in the Bug Reporting section.

Although, it may be possible that you're targeting a block near the Tardis, but not the Tardis itself. What do you do in your attempts to resize the Tardis?

 The command is /blockdata x y z {scale:<scale>}

You don't have the right coordinates for the TARDIS, so just adjust that.

i figured it out I stand 2 blocks above the tardis and on the cords section I do ~ ~-2 ~ you can lock the thread