Change to Norton....Free for 2 years or not?

[#1]

Today I got a letter from Plusnet saying they were switching to Norton Security....

"...And the great news is as a Plusnet broadband customer you'll get anti-virus protection from Norton free of charge for the next 2 years and after that Norton will be in touch..."

However, when I went onto my account to activate the product, it says it is free for 3 months then £2 a month.

I phoned Plusnet to query this and the person I spoke to insists that, on the package I'm on, it's only free for 3 months, not 2 years.  Would you challenge it?  I have it in writing, so do I have a case?

[#2]

What package are you on?

[#3]

Unlimited fibre including line rental.

[#4]

It's only two years free trial on fibre extra and above.

[#5]

Ah.  I was afraid you were going to say that!  I'm not sure on that one.  Hopefully someone else can advise.  I'm certain it is 2 years on Unlimited Fibre Extra, though not sure on Unlimited Fibre.

Edit: Thanks @dvorak got there first, with more info!

[#6]

Ah OK, thanks for the info.