dissatisfied with the service received from FNB HR

I worked for FNB home loans for 8years. I resigned from my post on the 29th of February 2016 to go back to school full time. Upon my resignation I was told that I will receive my pension after 6weeks maximum. On the 19th of April I received a call from a lady (Nthabiseng Maunya) of HR. She advised that there was a document missing in my claim forms and she will forward it to me to complete and return back to her, which she didn't. I called in on the 29th of April and Nthabiseng claimed that she did forward me the documents and advised she would resend them. I completed that document and sent it back to Nthabiseng on the 29th of April 2016. I sent Nthabiseng an email on the 2nd of May to confirm if she did receive the documents and I received no response from her. I sent another email yesterday morning and again, no response received from Nthabiseng. I then decided to call Momentum (as our pension fund is administered by them) and to my surprise, they advised that they received notification from FNB dated 03/02/2016 that I have resigned but they haven't received any documents from FNB confirming same. I then decided to call Nthabiseng as she has been ignoring my emails, basically she says I'm to blame for the delay as I was suppose to make sure everything is in order before leaving. I'm hurt by the way Nthabiseng and FNB has handled this matter, and yesterday I received a call from FNB threatening me with legal actions on my home loan account as I have missed 2 payments.