caliper and pads are ate up in less then 30 days on the back passenger side
My car has an automatic transmission.
Hello, well it sounds like a common issue in the braking system. One thing I would make sure of first is replacing both calipers (one axle) at the same time. The braking system is a hydraulic system and if there is any kind of restriction is the brake fluid system it will cause more pressure to be applied on one side of the axle.
My first attempt at fixing the problem would be replacing both brake calipers. However, to avoid any unnecessary repairs, I would suggest having your brake system diagnosed by a certified technician, like one from YourMechanic, in order to isolate the problem firsthand. Best of luck.