Its the passenger's responsibility to ensure that all names match the document used for travel. Whenever I make a reservation whether its using an Online Travel Agency or directly through the airline I check the itinerary as soon as they send it to me. If there is a problem I am on the phone before the 24 hour period to change it.
If you wait too long as you have found out and there are more than three errors either you pay a ticket name change or must purchase a new ticket. Its for security reasons and the airline may make an exception and waive the fees but its not guaranteed