Hobbits to Isengard - Q/A with Sapience notes on what was said

[Mar-Evayave]

There were only five wizards though, not seven

Perhaps he meant the Maiar in general, though even then there are more than 7. In addition to the two blues, Radagast, Gandalf and Saruman, Sauron was also a Maia, and the Balrog. Then there were some other Maiar from earlier on.