Like the title says.
I bought some BTC from a bitcoin broker. But I gave them a BCH address by accident.
They tell me bitcoin.com (my wallet) can help me out with this.
Which steps should I follow to gets this done?
Bitcoin.com is just one domain name used to promote Bitcoin. Bitcoin.com is not an official website. Just like nobody owns the email technology, nobody owns the Bitcoin network.
As such, nobody can speak with authority in the name of Bitcoin.