Manual Transmission problems of the 2005 Acura TSX

2005 cpo Tsx has clutch slip issue at only 56k miles. We bought the car as a certified pre-owned vehicle and within 4 months, the clutch needs replacement. When we took delivery of the car, we immediately noticed the car's clutch was not grabbing hard in 1st, 2nd and 3rd gear when trying to briskly accelerate. We notified the dealership and they're 'test drive' determined there was no problem with the car. We drove for 2 more months at which time, the clutch would slip when merging on the highway in 4th, 5th, and 6th gear. Dealesrship we purchased the vehicle from, elk grove Acura, is not taking any responsibility for the issue despite having documentation stating the clutch was slipping. They claim it's a wear item caused by us. The car will be going to another dealership local to us for a clutch replacement which we will have to pay for.