diff --git a/dnsapi/dns_world4you.sh b/dnsapi/dns_world4you.sh
index 9d36f84d..6baccbd0 100644
--- a/dnsapi/dns_world4you.sh
+++ b/dnsapi/dns_world4you.sh
@@ -52,17 +52,26 @@ AddDnsRecordForm[uniqueFormIdTTL]=$formidttl&AddDnsRecordForm[_token]=$form_toke
   ret=$(_post "$body" "$WORLD4YOU_API/$paketnr/dns" '' POST 'application/x-www-form-urlencoded')
   _resethttp
 
-  if grep '302' >/dev/null <"$HTTP_HEADER"; then
+  if _contains "$(_head_n 3 <"$HTTP_HEADER")" '302'; then
     res=$(_get "$WORLD4YOU_API/$paketnr/dns")
     if _contains "$res" "successfully"; then
       return 0
     else
       msg=$(echo "$res" | tr '\n' '\t' | sed 's/.*<h3 class="mb-5">[^\t]*\t *\([^\t]*\)\t.*/\1/')
+      if _contains "$msg" '^<\!DOCTYPE html>'; then
+        msg='Unknown error'
+      fi
       _err "Unable to add record: $msg"
+      if _contains "$msg" '^<\!DOCTYPE html>'; then
+        echo "$ret" > 'error-01.html'
+        echo "$res" > 'error-02.html'
+        _err "View error-01.html and error-02.html for debugging"
+      fi
       return 1
     fi
   else
-    _err "$(_head_n 1 <"$HTTP_HEADER")"
+    _err "$(_head_n 3 <"$HTTP_HEADER")"
+    _err "View $HTTP_HEADER for debugging"
     return 1
   fi
 }
@@ -111,17 +120,26 @@ DeleteDnsRecordForm[_token]=$form_token"
   ret=$(_post "$body" "$WORLD4YOU_API/$paketnr/deleteRecord" '' POST 'application/x-www-form-urlencoded')
   _resethttp
 
-  if grep '302' >/dev/null <"$HTTP_HEADER"; then
+  if _contains "$(_head_n 3 <"$HTTP_HEADER")" '302'; then
     res=$(_get "$WORLD4YOU_API/$paketnr/dns")
     if _contains "$res" "successfully"; then
       return 0
     else
       msg=$(echo "$res" | tr '\n' '\t' | sed 's/.*<h3 class="mb-5">[^\t]*\t *\([^\t]*\)\t.*/\1/')
+      if _contains "$msg" '^<\!DOCTYPE html>'; then
+        msg='Unknown error'
+      fi
       _err "Unable to remove record: $msg"
+      if _contains "$msg" '^<\!DOCTYPE html>'; then
+        echo "$ret" > 'error-01.html'
+        echo "$res" > 'error-02.html'
+        _err "View error-01.html and error-02.html for debugging"
+      fi
       return 1
     fi
   else
-    _err "$(_head_n 1 <"$HTTP_HEADER")"
+    _err "$(_head_n 3 <"$HTTP_HEADER")"
+    _err "View $HTTP_HEADER for debugging"
     return 1
   fi
 }
@@ -175,7 +193,7 @@ _get_paketnr() {
   domains=$(echo "$form" | grep '^ *[A-Za-z0-9_\.-]*\.[A-Za-z0-9_-]*$' | sed 's/^\s*\(\S*\)$/\1/')
   domain=''
   for domain in $domains; do
-    if echo "$fqdn" | grep "$domain\$" >/dev/null; then
+    if _contains "$fqdn" "$domain\$"; then
       break
     fi
     domain=''