Setting a fixed IP address for remote access to CCTV

[#1]

I have recently fitted a CCTV system linked to my smart phone via my Plusnet Router . Problem is the IP address for it keeps changing and i cant get any help from Plusnet support to tell me how to give the CCTV system a fixed IP address through the Router Settings . I am not IT savvy so am getting to the point where i will have to pay someone to come and do this for me .  

[#2]

You can buy a fixed IP address from PlusNet for a one off payment of £5.
Have a look here http://www.plus.net/support/broadband/products/IP_addresses_broadband.shtml?source=keymatch at section 3!
You buy the service and when they tell you it's been allocated you drop the connection in the router and then reconnect and 'BINGO!' your IP address will not change again!

[#3]

THanks for that. i took a look but my Router doesnt have the directories that it points you to. i am using a Technicolour TG582n

[#4]

OOps sorry ignore my last mail i just found it in My account.