Landcar Tried to rip me off Internet

We bought a used 2005 Hyundia from American Toyota a couple of years ago and got the extenend warranty from Landcar. A few weeks ago our transmission started acting up so we brought it to Larry H. Miller Southwest Hyundia. When I brought it in, I thought that my extnded warranty was had passed in Feb 2011, so I never told the repair guy. He called me back and told me my transmission had to be replaced and it would cost me $3,000!! I was in shock, I thought it was a bad sensor. I called Landcar and then found out that my extended warranty did not end until 2012. I called Southwest Hyundia back and informed the repair guy it was under warranty. He said he would order the transmission and get it fixed and all we would have to pay is $100.00! Well, two weeeks went by and I finally got a call that it was ready. I went to go pick it up and they had only replaced a sensor!!!!!!!!!! They said that LANDCAR did not authorize the transmission to be fixed! So basically they replaced a senor that costs $67.00. Seems to be that when they knew we had to pay out of pocket, we had a bad transmission and when they found out it was under warrany is was a $67.00 part! They tried to rip me off instead of being honest....sad! They also said that if the car starts acting up....and they think it will..... to bring it back and they will replace the transmission. They basically put a Band Aid on it to save money. Thanks!