fix(Payment Entry): get contact details from existing contact (#40556)

diff --git a/erpnext/accounts/party.py b/erpnext/accounts/party.py
index d8ae2a4..4b3f0c8 100644
--- a/erpnext/accounts/party.py
+++ b/erpnext/accounts/party.py
@@ -282,9 +282,7 @@
 	pass
 
 
-def set_contact_details(party_details, party, party_type):
-	party_details.contact_person = get_default_contact(party_type, party.name)
-
+def complete_contact_details(party_details):
 	if not party_details.contact_person:
 		party_details.update(
 			{
@@ -315,6 +313,11 @@
 		party_details.update(contact_details)
 
 
+def set_contact_details(party_details, party, party_type):
+	party_details.contact_person = get_default_contact(party_type, party.name)
+	complete_contact_details(party_details)
+
+
 def set_other_values(party_details, party, party_type):
 	# copy
 	if party_type == "Customer":