You need to tell them you recieved a text with a link which you followed and it said this at the bottom
" Finally because of the 3 Like Home change, it's only fair that we point out your right to end your contract with us, without paying an early cancellation fee. However we very much hope it won't come to that because we still believe we offer great value rates and great coverage. "
You will be on the phone for about an hour, but just tell them you've booked a trip to australia in JULY and this change will severly effect your bill as you was gonna use 3 like home to keep in contact with friends and family back in the UK.
they will be a bit arsey and in denile at first but just be adimant and read up on the ins and outs in my initial link first. It will give you all the information you need. Just be firm, and tell them legally you have rights to cancel.
theres more info here.
Do the changes to 3’s international tariffs mean you can cancel? | BitterWallet