Hi Armen,
If you can give me the date of either your wife's outbound journey, or the date of her return and a booking reference, I'll make sure this is investigated and a response will be on it's way to you. PM me with the details please.
Generally, in line with most IATA airlines (which Aero is not) Virgin Nigeria charges 10% of the applicable adult fare for infants under 2 years of age not occupying a seat. This should have been made known to your wife when she turned up at check-in with an infant and no ticket.
Alphaita ganga doesnt need a reply and I wont go into detail here of my own bad experiences on many other airlines around the world including Aero. At least he got an email last year while Aero have not yet replied to mine after 10 months. Alpha, you got a very quick reply from the FOD and an immediate change to procedures, so don't say "eventually" as if it was delayed.
Armen, there is a link on the VK website to the Customer Relations team who would investigate this and they would be happy to hear from you. Unfortunately, the phones are geared mainly to sales (call centre, groups, agents etc). Not saying that's right, just explaining why you havent been able to speak to someone over the phone.