If you need this doing quickly, I suggest that you contact a NOW TV representative via the forums 'Live Chat' facility and explain your requirements to them instead of requesting them...
The easiest way of accessing 'Live Chat' is by using a Windows or Mac computer, along with various many makes and models of mobile phones and tablets (provided their screen resolution is high enough). Here's what you need to do: -
• If I've been helpful please press the THANKS button • If I've been really helpful please also press the ACCEPT SOLUTION button • Please note: I'm not a NOW TV employee, I'm a regular NOW TV customer, like you! •
• LG TV 1 = Model no: 43UH668V | Software: 04.30.70 | OS: webOS 3.31 • LG TV 2 = Model no: 65UH770V | Software: 04.31.10 | webOS •
• All TV's = NOW TV app: 2.27.0 | Post Processing Features: All disabled • Networking Spec = ISP: Virgin Media (75Mbps) | Devices connection type: Wired | IP address type: Fixed (device permitting) •
This guide help article will explain how to manage your devices.
If you have the maximum four devices already allocated to your account and have made the one device change per a calendar month, then your only option is to contact live chat and explain to them the circumstances why you need to remove and add an additional device this month.
Hopefully live chat will be able to assist you further.
Here's a link to live chat.