Bit of a long shot, but if you know the server (which i am assuming is Official) and the exact time/map you played on, then the demo may still be available for that particular game in which the "deliberate" blocking tanks/pushing you into enemies would be visible.
If in doubt there is always a !modrequest feature within server that will alert any mods (granted it may not be instant reply, as we know everyone has different time-zones but i am sure they will respond asap) if it's went un-answered your next best bet is to go into discord (link above) discord is pretty active. You can also take screenshots which would further help.
But as alternative there is a ignore feature within the game (but you need to do it every map i believe from what i remember) press F5 ignore NAME (i think that's the command) saves a lot of agro
*Sidenote*
I don't condone any of the above, but it's not my place to say who/what is right/wrong. hopefully this becomes an isolated incident and going forward both can put there differences aside and enjoy the game as many users do. there is always going to be little issues that creep up here and there, but we just have to rise above it, not let it get to us and continue to maul GDI base defences.