consegui mudar de IP depois de cerca de 3 meses com o mesmo com este post do forum.
Para quem estiver interessado, basta copiar o seguinte script e colar no bloco de notas e guardar como ficheiro .vbs; "ex: meo.vbs"
Set cloner = CreateObject("WScript.Shell")
cloner.run"cmd"
WScript.Sleep 500
cloner.SendKeys"telnet 192.168.1.254"
cloner.SendKeys("{Enter}")
WScript.Sleep 500
cloner.SendKeys"sumeo"
cloner.SendKeys("{Enter}")
WScript.Sleep 500
cloner.SendKeys"bfd,10ng"
cloner.SendKeys("{Enter}")
WScript.Sleep 500
cloner.SendKeys"dhcp client ifdetach intf=InternetGPON"
cloner.SendKeys("{Enter}")
WScript.Sleep 300
cloner.SendKeys"dhcp client ifattach intf=InternetGPON"
cloner.SendKeys("{Enter}")
WScript.Sleep 300
cloner.SendKeys"exit"
cloner.SendKeys("{Enter}")
WScript.Sleep 100
cloner.SendKeys"exit"
cloner.SendKeys("{Enter}")
Para quem tem ADSl colocar no lugar de InternetGpon colocar InternetADSL