How transactions are done
Usually I work like this:
1. The fee is paid.
2. Seller sends me the goods or account login details, where I double check and confirm (on live stream) with the buyer if everything is as it should be. In case of an account I temporarily change email and login details.
3. The buyer pays the seller directly and records it to have a proof of payment.
4. After the seller confirms payment
I send the goods to the buyer or give him access to the account where he can change email and login details to his/hers.