Good morning, @Duff. Thanks for reaching out, and welcome to the Virgin Plus Community.
For us to be better able to assist, could you please clarify as to what exactly is happening when you try to reset your password? Additionally, how do you know you have people from outside your home connecting your home internet?
Additionally, we would recommend running our Virtual Repair Tool, and if needed, give your modem a factory reset. If you're unsure as to how, check out our Vincent support guide and scroll down to How to reset my Vincent modem to factory settings.
Looking forward to hearing back from you. Best wishes.