i had a new clutch installed last weekend and now its slipping after 150 miles. what could it be besides a bad install job? i had the clutch master and slave cylinders replaced and then the my last clutch started slipping now. i replaced my clutch and now its still slipping. could it be a bad clutch master or slave cylinder? thats what nissan said when i brought it to them but then they said clutch job....i think to get my money (both the clutch master and slave cylinder and the clutch were done by two different places)

 

anyone....what could it be?