Cement sheets in the bedroom wall - any ideas?

hi my daughters room has cement sheeting (panels) that make up her walls and roof and it looks really bad. I can see the joining lines even though its been painted over - do i have to remove all the walls and have the walls re plastered? is there any handy hits to fix this up? not sure you could putty up the lines and sand back as the boards currently up have big grooves - i did think about wood paneling around the room but you would still have the roof issue and the board lines above the panels - looking for a cost effective solution. Thanks heaps