I have just had to replace the push flush on my toilet. That is now working fine but I am having problems with the refill, IT JUST Won't STOP. Any ideas how I can stop this.

What type of fill valve did you install? Here are 2 common types. https://www.askmehelpdesk.com/attachments/plumbing/12875d1224099054-toilet-noise-clip_image001.jpg Both stop filling when the ball float is raised. How high up on the over flow tube does your water level reach, could float may just need adjusting downward.