Because a catalogue is considered a non-priority debt, they do not have the power to send bailiffs to your home. They can send you intimidating letters which may suggest otherwise, but only the courts have the authority to send bailiffs.
A catalogue can apply for a County Court Judgement (CCJ) against you to get back the money you owe. The court would implement a payment plan for you to pay your CCJ and only if and when payments aren’t adhered to would the courts then have the power to send bailiffs on behalf of the catalogue.