Hi,
To request an amendment or cancellation after clearance of an import declaration, you must notify HMRC using either a voluntary clearance amendment, underpayment, C2001 or repayment of import duty and VAT if you have overpaid, C285. More information can be seen here:
Amend or cancel a Customs Declaration Service import declaration
CHIEF is decommissioned so no imports/exports can be made on it. The information on the status of clearance can be found from either the importer or declarant. HMRC does provide historic data of declarations, please see link guidance below more information:
Request Customs Declaration Service data on imports and exports
You can claim for repayment if you have overpaid import duty and VAT. In some cases you may also be able to claim if you have overpaid excise duty. Please see below link for more information:
How to claim a repayment of import duty and VAT if you've overpaid
Thank you.