Starter Relay problems of the 2006 Chevrolet Impala

My 2006 chevy Impala will not turn on. I replaced the battery and starter with the same results. Starter relay is also good. I have researched this problem on the web and to my horror, this is a common problem with this vehicle, with very high dollar possible solutions that may not work. Every time I bring in this vehicle I am charged 100 dollars for them to say what is wrong and when they (supposedly) fix it ( or say it did not do it with them and its all in my head and your doing something wrong to it), it does it again. The charging system is ok but there is no power at all thruout the car but if you wait a couple of hours it will show lights but it will not even crank and then go completely dead. This same problem has happened from every other customer who has had this problem and cost them plenty of money without a solution. I have researched youtube, yahoo answers, fixit, etc. . . And this is what all these other numerous customers are saying even when they went to the chevy certified mechanics throuout the country. I do not have the resources to keep paying for diagnosis and numerous possible fixes that does not remedy the problem. Bringing the vehicle to a chevy dealer for them to charge me an arm and a leg to not fix the problem ( and no they will not give you a refund for not fixing the problem that they charge a 100 dollars upfront to diagnose). This is not the only problem, the transmission slams into gear especially when you come from a start or after you back up and drive forward. This is not normal but chevy will say it us. I take pride in keeping my car running so I know it is not from neglect or abuse this is simply an ongoing problem that these chevy vehicles have because I m seeing this exact same problem on their other models throughout multiple year spectrum. This is ridiculous!!! all these consumers across the country are not wrong.