CAN I TRUST THIS???? 00 Maxima clutch issues or shop error?

[NavsMax]

Guys, I am having a hard time trusting a shop... My Maxima's clutch/transmission was working just fine except for a pretty deep clutch pedal. When The clutch pedal finally got stuck in the floor I took it into the shop. They replaced the master cylinder and slave. After it was "fixed" the clutch pedal would change resistance from soft to hard and then back to soft. These changes would happen after a 10-15 minute drive. They said there was probably air so they leaked it and they siad it went away! Nope... it conituned to happen but I decided to stop taking it back. Now, a week late, I noticed that I would drive and the rpm would rise as I stepped on the accelerator but the car would not accelerate!!! Again, I did not have this issue prior the replacing the master cylinder and slave. What do I do???