Firewall / Router redundecey

Greeting all, this post is more a networking/ redundancy question but here it 
goes anyway.

I have many remotes sites. Each site has 2 high speed connections available 
(ex. 17.16.12.1 and  172.16.12.2). Each site also has a layer 3 switch (primary 
IP gateway of 172.16.12.2) capable of link aggregation and VRRP. The catch is 
the redundant connection is via a Cisco 3950 (IP of 172.16.X.1). I have no 
access to this device. It is part of a large province wide supernet project and 
I can't make config changes to the device. This takes out the possibility of 
VRRP or Link aggregation. Right now for redundancy I can buy an addition 
service that will give me OSPF on the 172.16.X.1 device and of course add OSPF 
to the 172.16.x.2 interface and simply wait for convergence to give me the path 
to our central office 172.16.128.1, which in turn has balanced T3 connections 
to the internet. This however is a huge cost increase and I can't believe that 
there isn?t a cheap and easy fix to give reliable redundancy and or load 
balancing. Right now I am looking at WAN balancing hardware de
 vices or a Linux box with 3 NICs, one acting as the gateway. Does anyone have 
any good ideas how to manage the redundancy for this? I feel like I am missing 
an easy fix here.

Thanks