Has anyone else had a problem with their s4 where it sometimes won't let you pull down the notification bar? If you then dial some numbers and call it then works again. Driving me mad now I've googled it but no solutions

Have you updated to Jelly Bean 4.3?

Yeah its on 4.3 but always had this problem

Have you backed up your phone completely, because I would suggest a complete factory wipe & reset.