Garrett Motors

I had my heater on my def tank repaired under warrenty. then thing started. I get home and my check engine light comes back on. this time they said my heater box was bad. 879.24 dollars latter fixed so I go home and light comes on again. this time it's the knock sensors. 1070.47 latter I pick truck up and go home. on the way light comes on so I stop at auto zone. computer said heater box and knock sensors both bad. dealer said bring it back so I drop it off that evening with auto zone read out on seat. next day they call and said nothing wrong, no check engine light on. take truck home and a few days latter light back on. take it back to garrett motors with light on. reads heater box and knock sensors bad. they call an said they found the problen was a defective fuse for the box and sensors. I spent a total of 1949.71 to find out it's a fuse. they won't give me my money back. said parts were bad. thats bull because no problems until def heater was fixed. as many times as they had it in the shop for check engine light the problen was in fuse. going this way for my money back. do not want to see a lawyer but will seek advise other wise