Try another charger for the same Tablet, if you can. Your friends or neighbours may have one. They are everywhere you look...you could try mine if we lived closer ! Check if a fuse has blown in the plug attached to the charging lead, if it has one. ( I have a 7 inch Samsung Tab and my charging lead doesn't have a fuse )
These plugs that go into the Tablet are easily damaged, if an attempt is made to put it in upside down, which is easy to do, so have a close look at the socket and the plug, to see if any of those tiny little gold-coloured bits are broken.
If not, go back to PC World. Perhaps they could tell you if its the charge lead or the tablet on the spot. Charging leads are not expensive, so it might be quicker in the long run just to buy a new lead, rather than wait weeks for PC World to act under the guarantee. Sorry I can't think of anything else that might help. Please let us know what the solution is, so that we can all learn.