@Kim3033
You can do it yourself.
1. go to the message thread you have for that booking on the Apps
2. on the top right (on the phone) there is a button called « details ». Note that it may be placed somewhere else on the screen if on a computer
3. at the bottom of it (just above the frequent question section) you will see few option, one of which is request or send money.
hope it helps
.
Annie