If the Home Office officials detect serious offences and the sponsor licence is downgraded to B-rating, you must contact the Home Office within 10 days. For an additional fee, you will obtain the so-called plan of action that will give you instructions how to upgrade to an A-rating.
If you fail to contact the Home Office, it will revoke your licence. Besides, B-rated licences offer only limited opportunities. For example, you won’t be able to issue new certificates of sponsorship till you are upgraded again.