You must do a lot of driving to wear out the brakes in five months.
Well maybe and maybe not!
OK Paul first don't think I'm picking on you, or saying your stupid or something here.
But so many times I see folks who drive these beasts that have not been around them for yrs who have no idea the proper way to release a set of DD3's. And many times will brive them all over the place with them partly still on. Which in turn wears them out faster!
OK that said the proper way to release DD3's is to let the bus build air up to the max pressure (spit off).
Then Depress the brake pedal while pushing down on the brake release button. Once the button is down push the brake pedal all the way down for 3-4 seconds then release. The brakes should now be completely released. Failure to do this properly can result in one or both of the brakes staying partly or even completely engaged. While most times it is noticed right away by a seasoned driver, sometimes drivers not used to buses or that particular bus will think "man this thing is a dawg!" And not knowing it will be working the engine & trans HARD but still able to drive it!
OK now that said, it also does not say that it is Pauls problem here either!
It could be that ABC told Paul the brakes were good to go when he bought it so that the cost of repairs didn't scare him away and cost them a sale. (once he owns it it doesn't matter what it cost to fix it, because they done sold it!)
SO it could be either of these or it could be something all together different too!
Paul good luck and let us know how it turns out!