Who to talk to in order to purchase more usage of the vtext.com email-to-sms gateway?

[nvrslowdown]

I have creating software that allows an organization to send text notifications to all of their members.I was told by Verizon tech support that I need to purchase more rights to this email-to-sms gateway (vtext.com and vzwpix.com) for my software.

Who do I talk to purchase this?

I have spent over 5 hours on the phone with Verizon with no luck.