I have a new setup, here we have 3 routers and two ISP.
I am running OSPF and IBGP in my company. Let named then as A, B and C.
A is connected to ISP X and C is connected to ISP Z.
OSPF is running on A, B and C.
IBGP is running on A and C with loop Loopback interfaces address as neighbors address.
I have configured static routes and give default-information originate command under the OSPF process on router A and B.
Router B is loading balancing in a round robin manner.
What I want that one ISP goes down whole traffic to shift to other and when the ISP come back loading start again.