In the US, there is a government sponsored agency called the Better Business Bureau (BBB), if a consumer has a problem with a business, you file complaint and they look into it, contact the business with the issue ans most of the time things get taken care of .
Other route, is if your local television stations has any sort of program, usually on the evening news, a consumer complaint/help with problem businesses .
From what I've seen, as soon as the business gets some 'bad' airtime, the issue is quickly resolved .
Good luck, I had problems with two businesses about 7 years ago, one rebuily the transmission on my '81 R65 and the other relined the clutch, they nade mistakes on both .
One letter from the BBB and the issues were resolved to my satisdfaction .