VPN over LTE not working!!!

I am trying to connect to my companies VPN although through the Telkom LTEA service i am unable to i have been waiting on the call center for over 50 min for a consultant to assist with the issue. Why am i unable to access the vpn but with a Cell-C or MTN connection it works perfect? Please can Telkom provide answers and how can this work with the Telkom LTE service.