AOS FEE PAID FOR ONE PARENT GOOD FOR BOTH?

[tasnim 1]

There are many threads here on the subject of AOS fee for parents. most of the members have shared that the AOS fee paid by them for one parent was good for both the parents and after payment of fee in one case the fee status in the case of other parent showed as PAID. I petitioned both of my parents in November 2013. my mothers case was approved and forwarded to NVC in May 2014 whereas the case of my father was sent to NVC in September 2014. I paid AOS fee($88) for my mom in July. Now NVC has raised invoice of AOS fee($ 120) in my fathers case showing it as NOT PAID. I checked NVC site under FAQ and it says that each case needs to be paid AOS fee except concurrent processing at nvc in the cases of USC petitioning spouse/child. I am confused and trying to call NVC for last three days but could not get through. There is always a busy tone at their end. I have contacted NVC through email though but don't expect their response soon. I need advice of VJ members in this regard. Should I pay AOS fee for my father or wait for their response to my email.