A lovely plumber did a job for me this week. He’s done work for me previously. I asked him to tell me how much I owed him. He said pay whatever you are happy with. I said I don’t know and want to pay him fairly. He left and said I had his bank details. Sent him a message asking again and he said the same thing. I’m getting quite frustrated and don’t know what to do. I don’t want to pay too little or too much. Any advice?