Septic/Drain Field Problems

My house will be 5 yrs old in May. Last year we finished the basement (we have a split foyer). In that we added a full bathroom. A few months after everything was finished, the basement toilet started to gurgle, not flush fully, and finally starting overflowing. We got our septic pumped out and were told that we probably had a bad drain field. We hoped not, and hoped that cleaning the septic would solve the problem. A month later the toilet starting acting up again. We had the septic pumped again by another company and they concluded also that our drain field was bad. The septic tank is on the side of our house that slopes downward to the backyard (the septic tank being at the top of the slope). The drain field is in our front yard which is the highest level of our property. My question is: Is the builder in any way responsible for: 1)not placing these items in the correct spot or 2)not digging the drain field low enough? Also our concern is that the drain is not long enough. It is probably a little less than 50 feet long, should there have been two 50 ft. drain fields put in? Any help in this matter will help. Also, may I say that this particular builder has a great record for failing septic systems (which I am now finding out). He has never been responsible because problems do not occur until after 1 yr. when the warranty has expired. Shouldnt he be liable for something? Thanks for your time.