They are not going to file any claim. It's all a lie. You returned the product. They can't get you for $5,000 of shipping costs. That's a preposterous amount of money to ship a cell phone. For that matter, you can buy a dozen cell phones with $5,000. There's no way they are being truthful.
Also, BioLife sells health products and not cell phones. So this has nothng at all to do with that package you returned in the first place.
Scammers make these kinds of calls all of the time. Don't fall for it.
But if you're not convinced, you have substantial rights under a Federal act called the Fair Debt Collection Practices Act. You don't have to buckle to them just because they are claiming you owe them $5,000 but are willing to take $450. You can make them prove to you that you really owe this debt and then if you don't agree you can dispute that debt.
If they call you again, you can ask them for a validation letter in writing and then if you believe you don't owe it, you can dispute the debt if you don't believe that you owe it. You're entitled to do that under the FDCPA. If they won't give you any such letter, they are violating Federal law, which is one more way you know they are scammers.
If you get a validation letter and agree that you do owe this money, then you can make arrangements to pay it. But if you don't agree, you can write back telling them that you're disputing this debt. Once you formally dispute the debt, which you should do in writing, they MUST leave you alone. If they don't, you could report these folks to the Federal Trade Commission as they would be violating the Fair Debt Collection Practices Act and can be fined $1,000 for each time they illegally harass you to continue to try to collect money.
If they are scammers and not even real collection agencies, they are probably not going to be intimidated. However, once you tell them that you're disputing the debt, you can safely ignore them.
In the worst case scenario, if they are real and truly believe you owe this debt, they would have to take you to civil court and you could prove there that the debt has been settled or does not exist. But again, they would have to personally serve you with notice. A phone call or email doesn't count.
The Federal Trade Commission gives a wonderful overview of overaggressive and/or fake collection agencies and how to get them off of your back, where to report them, where to learn more, etc.
You can access that here: