You cant "prevent" the debt collector from reinserting their reporting, even though deleted due to their failure to have verified its accuracy during a dispute process.
The dispute process has a (normally) 30 day time period in which the CRA must either correct the disputed information, or verify its accuracy. If they dont receive verification from the furnisher within their required reinvestigation period, they normally have no other means to verify its accuracy (with the exception of, for example, a public record, for which they can do their own verification), so they delete.
That does not prevent the furnisher from later providing the missing verification, and getting it reinserted. Their reporting must be accompanied by the missing verification before the CRA can reinsert the deleted reporting. It is not common for a debt collector to go to that trouble, but CR deletion of disputed information is not absolute.
The bottom line is getting a statement of verification of accuracy in your file.
Failure to have verified with other CRAs does not negate any verification they provide to one CRA, so is not a basis for compelling the deletion of verified information with the one CRA. It may raise question about why they did not verify with all, but that is their perogative.
