Moen 1222 Cartridge won't maintain temperature

[MBMatt]

I have a five year old house and have had to replace the Moen 1222 cartridge every year. It won't maintain/respond to the handle adjustments. Example, usually the handle in 3 o'clock position provides proper temperature control. Today at 11 o'clock position it was lukewarm. I pushed it to the 9-10 o'clock position and now it's scalding hot. Moved it to 3 o'clock position and still scalding hot. Turned it almost off and still scalding hot when it should be ice cold. (Note: I waited a few seconds after handle adjustments to give some time for temp adjustments but to no avail.) After I replace the cartridge I'm good for about a year and then it starts all over again. No other faucets have this problem and I live in an area with soft water. Fortunately, Moen replaces the cartridge for free and I've asked them to examine/test my old cartridges but they're not interested. Just send me a new one. Anyone else have this problem or any suggestions?