BCH and BTC share the same technologies but are two different currencies, sharing two different blockchains. However, the wallet formats are the same. In these cases, you'll need to contact your wallet provider directly and ask them for instructions on how to recover BCH sent to a BTC address, as they are the only ones with the ability to resolve this issue.
If they need any information about the transaction, please let us know. We'd be happy to help; but ultimately, the ball is in your provider's court.