Pfister Kenzo 1-Handle Shower Only Trim Kit in Brushed Nickel

We purchased this over a year ago and loved how it looked in our new shower. About a month ago, we began having issues with the water not turning all the way off when put the handle in the closed position. I removed the handle and found out the screw holding the stem in place had come loose. That is when I noticed that the part that moves the valve for the water is made of plastic. The part on the handle that moves the valve is metal and you'd think that the part that it is turning to turn the water on would also be made of metal. A portion of the plastic, which holds the two pieces together, broke off. I just wish it was metal because I sense the plastic part will soon break off! It's a shame because it looks so nice!