Reply to Changing the tune / melody of an acapella to match another track.

Hey guys, lately i've been making tons of edits for my sets and shit, and i sometimes find acapellas with lyrics that would perfectly match an instrumental, but they are in totally different keys, and the tones/melodies just start clashing and won't sound nice even though they would go well together.

I use ableton, you guys know of any vst's that would help me change the keys in acapellas, say from 2A to 6A without killing the voice.