Yes Sorry I thought I did but I guess it was on another forum. Here is what I did:
Redirect to Nopay Site
/ip firewall Nat
add chain=dstnat action=redirect to-ports=8081 protocol=tcp src-address=172.16.50.1-172.16.50.254 dst-port=80 comment=”Redirect to Proxy” disable=no
/ip proxy Access
add action=allow disabled=no dst-address= 188.8.131.52
add action=deny disabled=no redirect-to="http://navigowifi.com/payment-reminder.html
You have to create a profile with that ip pool on pppoe server...
Hope this helped!!