The CBE Group, as a third party collection agency, is not able to process any transaction without your explicit permission. That permission ends with the first Non-Sufficient Funds transaction reversal. If a payment arrangement that you had agreed to caused your account to NSF, they would halt payment activities and resume collection activities, likely resulting in the phone calls that you are receiving. If you answer the phone and speak to them, those repeated efforts to reach you would then cease and you will be able to re-negotiate your arrangement with them. Are the transactions that you are referring to appearing as The CBE Group on your bank statements or in the name of their client, the original creditor?