If you do not pay a congestion charge what will happen?

Please pay it! It becomes a nightmare. It ends up with bailiffs at your door. If you have left it to late and it has got to that stage, you can fill in forms PE3 and PE2 which are an out of time form and a stat dec send to the court and the TFL will reissue charge at original charge. This forms will though have to be witnessed by a solicitor after you Have ticked the I did not receive notice to owner box!