Stuff happens. Hardware faults occur (with all providers almost daily). Some can be tricky to diagnose. You may think a problem is resolved only for it to occur again, leading to a conclusion that it's not actually the part you replaced that was faulty, but another underlying issue (such as a power supply dropping voltage under certain load conditions, but not at other times).
They'll always try the quick fixes first (to get the unhappy bunnies back online fast), and again these fixes may not last. But they'll always try and avoid a complete hardware replacement unless absolutely necessary (as they'll either have to route the bunnies differently temporarily causing slowdowns and more gnashing of teeth, or cut them off completely whilst replacing the hardware, making the unhappy bunnies even unhappier).
Again: stuff happens. Unless you have an SLA with your ISP, there's not much you can do about it.
It's not an indication of an ISP going "downhill", either.
- My journey back to xDSL after a decade with VM
Fibre 2 | Huawei HG612 via Fritz!Box 7530 | ECI Cab