Records of private businesses are private records. They do not have to be shared with genealogists. It does not matter how long your ancestor worked for the company, how much money your ancestor spent at the store, or how “bad” you need whatever information they have.
Private records are just that: private.
Some companies do maintain an archives and are willing to share information with researchers. The records of some defunct companies have been preserved in a public archives. Those are exceptions.
You can try and request information from a company for which your ancestor worked. But they are under no obligation to provide you with any information.