This is how I would fix the alphabet with the Alphablocks.
Alphabet[]
C: /k/ & /s/[]
As we know C makes the same sound as K as seen in Kick, she can also say the same sound as S when she stands by I, E or Y as seen in Space so this letter is useless to the alphabet. We can easily fix it by replacing it with K or S, (Kat, Spase) The only letter we need to bin.
Y: /ee/, /igh/ & /i/[]
Y can make the sounds /ee/ & /igh/ as seen in Why so we can easily replace it with digraphs EE & IGH, (Whie, Partee)