Create a batch file with the following content
@echo off
@echo "Disconnecting Connection"
rasphone -h "Vodaphone Broadband"
@echo "Waiting for 3 seconds"
timeout /t 3 /NOBREAK
@echo "Connecting to Connection"
rasphone -d "Vodaphone Broadband"
Just replace Vodaphone Broadband with your dial up connection name, and that should do it.
In case the timeout doesn't work, just replace it with "ping -n 10 127.0.0.1 > NUL", this will use
"ping" to create delay.