Cisco WAN :: 7204VXR / 4507R-E - Redundancy To Single ISP?

what I have are 2 x 7204VXR (Gateways), 1 x 4507R-E (Coreswitch), and our ISP have 7609.Got some issues with redundancy with our ISP.
 
                                        7609
                                        I     I
                                        I     I
                               7204-A    7204-B
                                    |             |
                                    |    vrrp   |
                                    |             |
                                    -4507R-E-
                                          |
                                          |
                               internal network
 
Both outside interfaces of 7204 gateways are connecting to 7609 with different public ip block.I used VRRP for my internal nework and failover have been tested working.Even tried to remove link of 7204-A and 7609, the failover works perfect.But somehow we're facing a problem:

- If I shutdown/ remove the link between my 4507R-E and 7204-A (primary gw_higher vrrp priority), vrrp redundancy/failover still works but internal network's internet connection goes down.
 
I asked our ISP and the route commands they put in their 7609 are as of follows:
ip route 3.8.8.0 255.255.255.0 3.4.4.4 name TO CUSTOMER LINK 1
ip route 3.8.8.0 255.255.255.0 3.3.3.3 2 name TO CUSTOMER LINK 2
 
And if they're trying to use Reliable Static Routing Backup Using Object Tracking, the internal network's internet connections is intermittent....alternate 4 ping reply and 4 timeout.
 
Note: IP used are sample only