While it may seem straightforward to call off debt collection after you've submitted an account to a collector, the situation may not be quite so simple and is worth understanding before engaging a collector (through CollBox or otherwise).
The short answer is that you typically cannot cancel a placement during the collection period without paying the fees the collection agency would be due on a successful collection—unless the agency chooses to allow it.
Most collections are done on a contingency basis—this means that the collection agency only gets paid if they are able to collect for you. As soon as you place an account into collections, the collector will go to work tracking down the debtor (as needed) and then seeking payment.
Sometimes, after a very brief period, the debtor may contact you to make payment. In these cases you may then wish to cancel the placement, thinking that the services of the collector were not required. In reality, however, it's likely that the debtor chose to make payment precisely because of the collector's actions. And while it may seem like the job didn't take a lot of effort from the collector (given the quick results), in truth a quick payment is exactly what you're hoping for as a business owner.
Since it's difficult to conclusively tie the outcome of a placement to the actions of the collector (versus another cause), the collector is given rights to their fee on any money collected by either party on the account during the collection period. This avoids difficult disputes; it also means that an account cannot simply be cancelled without fees, otherwise creditors could immediately cancel placement any time they took a payment, leaving the collector uncompensated for their work.
With this in mind, you should typically only engage a collector when you no longer believe you'll be able to collect the account balance on your own. Once you've placed the account into collections and into the hands of a professional, you no longer need to make your own attempts to collect. The collector will have exclusive rights to collect the balance for you, and you can rest assured that if the debtor does pay, it's almost definitely due to the actions of the collector.
That said, if you place an account in error, please contact us or the collector as soon as possible, and we'll do our best to cancel the collection. The decision to allow a no-fee cancellation ultimately rests with the collection agency, but the sooner you act, the more likely the agency will be to allow the cancellation.