Maul (Hate-Fueled) Stuck at Level 52

I spent crystals getting all five characters to four stars so that I could unlock Maul (Hate-Fueled) only to discover that you don't get enough level up mats f2p to take him above 52. I've cleared tier 5 on all four coliseum bosses and so the only way to get more Mark V Cresh materials is by spending more crystals. 

This is a ridiculous hidden charge that should not exist.