Bad Service from poor Automotive repairers

They have my car for 3 weeks now to replace a clutch that is still under warranty. they promised me that I will have it back on 11 August 2021 at the latest and still they are not done and keep giving excuses, surely it doesn't take 3 weeks to replace a clutch, it takes about a day to do it. I can't do my work because I need to see clients and my employer is starting to think that I am lying. Can someone please do something about them so that I can get my car back in this week because this is ridiculous