Instead of moving legally, can I stop a debt collector from contacting me?

Did you ask for the validation? If no, then ask for it as soon as possible. However, if you have good income, you can consider debt settlement to stop collection calls.

You can at first ask for the debt validation letter.
Then after validating the debt, if you can't negotiate with them on your own, you can contact a consolidation or settlement company to negotiate and handle the debt repayments on your behalf.

You can send a cease and desist letter to stop a debt collector from contacting you. But if the debt is valid, then I would suggest you to send this letter. But if your plan is not negotiate with creditors directly, you can certainly do that. No issue. You can write in the letter that you want to settle with your creditors directly.

If you just need time to pay off debt, then tell that to the debt collector. Don't send the Cease and Desist letter in that case.

I would agree with Patricia.
You may enroll in a debt settlement program to settle your debts. THe debt settlement company will contact your collection agency to stop collection calls.