Can an ASE certified mechanic shop refund my money back if I am not satisfied with work?

(Dallas, TX)I have returned my personal vehicle(2001 Chevy Tahoe) three times now after a "check engine" light they claimed they diagnosed and "fixed"came back on.I paid them on two different occasions for different parts and labor on the same problem, same diagnostic code. Each time I returned my vehicle was a different part that needed to be replaced. I have not only wasted valuable time, but money on the parts and labor plus rental car fees. I plan on asking for a full refund (including parts and labor) tomorrow, but wanted more information before I do. Helpful information on subject only please, no childish remarks.