Network Channel Bonding with a Twist

Hi all,

I've got a question for the community, currently I have internet service from COX communications here in San Diego (300 Mbps Down, 30 up) and I have ATT ADSL that was bundled with my home digital phone (10 Mbps down, 1.5 up). Since COX added their data cap of 1 TB I've come close to hitting the cap, I'm looking at taking the plunge into DirecTV Now as my only TV provider and I know my internet usage will increase.

Here is my question, I would like a Failover/Load balancing router that will fallback to the ATT ADSL once I have hit my data cap. Does anyone have a solution or recommendation? Most of the routers I've found do have failover/load balancing but not with the connection switching event occurring after a data threshold is reached.

Currently my network is a follows:

COX-> Google Onhub x3-> device

ATT (different wifi network)-> device

What I'd like:

COX (1st TB of Data)_________

ATT (Once Cap exceeded) ___ > Google Onhub x3-> device

Thanks for the Support,

Erik