Almost a complete loss of power

Umm i have a mazda6 2006 and my car was doin the samething had it put on computer it read bad (tcm)transmission computer no one could fix this problem but mazda so they say but took it to mazda dealer pay for them to have put on the computer to make sure it was the problem told me to leave car and tell will call before any repairs was done i waited and no call until closing time told me they repaired the problem they said bad wire from the tcm and i paid them and as they was pulling my car around aloud knocking from my motor that wasnt there before i took it in and no one could tell why and refuse to help me but i had drove it home got it check out again more money tells me i need a new motor