Your friend is cheating.
There is a combo by which you can cast a 9th level spell at 6th level once per day, but that's only for a cleric. It involves Divine Metamagic, Heighten Spell, Sanctum Spell, and Extra Slot, which combine to give you a single 9th-level spell slot. That is the cheesiest possibility for low-level spells available outside of infinite power, however.
D&D 3.5e is really not /that/ broken (not nearly as broken as you think it is) unless you want to actively break it. Then it becomes ridiculous.