Sent BCH to a BTC address in my wallet
If you don't possess and control the according private keys, you don't "own" Bitcoins. Maybe you have a right to access and transfer your Bitcoins and maybe legally "you own them", but not technically.

If you have sent BCH to a BTC address, then, only the according private key of that BTC address could help you sending your BCH out of the accidentally used BTC address.

Either you import that private key into a BCH wallet that supports importing private keys or you directly create and sign a raw transaction (experts only).

Blockchain.info could easily do that for you, but I don't expect that highly centralised services will have the man-power to follow such support inquiries.

Also, they could collect the accidentally sent BCH (don't I don't think they do).