Tank Filler Pipe And Cap problems of the 2001 Dodge Dakota

Abs & brake light and check engine light came on on our 2001 Dodge Dakota quad cab with 43,000 miles. Took to norwin Dodge for service. They found that the differential (rear end) was completely ruined. Since vehicle was out of warrently our out of pocket expense was in excess of $1,600. 00. Also said that engine light was due to a moderate evaporation leak and replaced gas cap. The transmission of this vehicle also had to be replaced after only 4000 miles!(fortunately this was covered under warrenty), but a complete transmission replaced after only 4000 miles? also had vehicle back to be checked after transmission replacement because it would hesitate and then shift hard. We were told that that is normal and how Dodge trnamissions shift? we take very good care of this vehicle and had it serviced regularly. Want to register formal complaint and make others aware of poor quality of Dodge vehicles and potentially defective products used?.