Cancelling due to price increase?

[#1]

I'd like to cancel my plus net package due to line rental increase.  Am I able to do this?  I had no notification of any increase, only just hoped when I looked at my bills.
Any advice? 
Thanks x

[#2]

No as the time limit for cancellation is well past
You will have been notified of the price increase in July last year

[#3]

The line rental went up last Sept. You should have gotten an email then telling you. The limit for getting out was back then.
You could try the retentions team to see if you can get a better deal.

[#4]

No email ever received - trust me I am OCD about such things. 

[#5]

Looking on the account it appears we sent the email notification on 29/07/15. A copy of the email was put on the account Here.