I have an 18 month contract due to end in April 2019 for unlimited broadband. The connectivity is awful so I want to switch to sky, my previous supplier - Plusnet increased the cost of my broadband in July so does this mean I can switch to Sky without incurring any charges because Plusnet broke the original contract?
Fixed! Go to the fix.
Welcome to the forums @misstsparkle
The increase in cost in July meant that you would have had to leave before that date to get out of the contract without early termination fees.
The rule is that the ISP notifies you at least 1 month before the price increase (Plusnet use email) and you have 1 month from that email being sent (not read/received or whatever) to ask to leave without any fees.
So you are out of luck on that front I'm afraid.