Hi there, first post so apologies if this is in the wrong place but had some issues with my toilet, it's old but started leaking out of the handle, the overflow pipe in the cistern appears to be full. It runs outside so likely frozen, it's an old ground floor extension that has been really cold due to the build. I need to replace the ball float valve as I don't appear to be able to adjust the height but worried about the blocked overflow. Any advice on what I can do to unblock or how much it would cost to have the system converted so the overflow is part of the flush system? Thank you.