change modem

[#1]

What do I need to do to get a new modem as my phone exchange has been updated to adsl2 21

[#2]

Do you need one - which one do you have at present
If you do there are two basic option - buy one or sign up for !2 months with Plusnet and get one for £5.99 P&P
With your existing connection what is the reported attenuation