I work for a company that has one owner he also has a cafe in his store. I work 6 days a week 48 hours. The cafe is under a different company name.

The employer cannot avoid overtime simply by having you work for 2 different companies that he owns.  But this does not automatically mean you are entitled to overtime.  It will depend on many things such as the work you are doing, whether the owner carefully follows the rules that apply to him to keep the 2 companies separate, and few other facts. You should meet with an attorney who specializes in this area of the law and he can answer your question after reviewing all your facts