It sounds like you need a cGMP compliant partner in a big way.
Right now, you’re probably operating in a world without an FDA Current Good Manufacturing Practice (cGMP) compliant supplement fulfillment partner. Even if you do have a 3PL, the above problems are certainly indicative that you need a big change. Selling edible items, including vitamins and supplements, requires extra care that a general 3rd party logistics facility may not be taking.
After all, it’s just a supplement, right?
Wrong. It’s a perishable and fragile part of your inventory. When your customers are constantly complaining, you’re having to handle a large volume of returns and discount deeply just to continue to attract customers, you’ve not got much of a eCommerce supplement business. Inconsistent quality and unpredictable returns are what you get in a world without FDA cGMP compliance.