The deposit return takes ages

The process of renting a car and returning it, including the price range for the hire is very favourable and great for the customer. On that part, I will. rate them 5 stars. My main issue is with the return of the deposit that is held on my credit card. 7-21 business days is beyond ridiculous and unfair to be honest. What is the hold up really, there is no explanation or justification for it. I am greatly disappointed (it's been 8 business days and still waiting)