Well after all that I've worked out how to delete podcasts not recognised by itunes on my own. Which is just as well seeing as how helpful iRobot closed my question without anyone answering(in what way does my question not hold enough detail to be answered?!?!?!!?) Anyway if you touch the podcast you want to delete and slide your finger/thumb to the left a little delete button appears on the right where the date of podcast is displayed. Hope this helps someone out there.
Just as an after thought. I had this problem for ages but solved it sort of by accident when i replaced a broken hinge. When I opened up my macbook the connector on to the logic/circuit board from the battery socket in the battery bay was loose. Pushed it back in and it's been fine and dandy ever since. Worth a try before you buy a new battery I would have thought.