Hi! This is my first writing to you.)
I wonder how you say in turkish "withdrawal statement"- in a case when a client quit the procedure he is in and deceide to resign. mesela from a refuge right. is it "haktan vazgecme"? But not "istifa mektubu". Maybe "feragat belgesi"?
Thanks!

"Feragat belgesi" is correct for "withdrawal statement". It is a bit old fashioned but those legal terms are like that in Turkish.

'Haktan vazgeçme' is the action not name of the document. hak: right, vazgeçme: give up.

We use "Feragat belgesi" in this case.

'İstifa mektubu' is completely wrong since it strictly means "resignation notice" which is what you give before you quit a job.