A single company does not get a /12 prefix. 2a00::/12 is almost half of the space currently allocated to all of RIPE NCC. Facebook seems to have 2a03:2880::/29 out of that /12, and a /40 through ARIN (2620:0:1c00::/40)
Is the notation the problem here? IPs have 16 bytes now, so the notation is a bit more compact: hex instead of decimal numbers, and :: is a shortcut meaning "replace with as many zeros as necessary to fill the address to 16 bytes"
