The 18th of April PCN, the earlier PCN being pursued by the bailiff is for "Stopped on a pedestrian crossing or crossing area marked by zigzags".
Be aware that unless things have changed this contravention can also be enforced by the Police. In which case you'd get a Fixed Penalty Notice and three points on your license. So I suggest you don't do it again.
Somehow lost in the post in less than five months are:
2 x Postal PCNs,
2 x Charge Certificates,
1 x Order for Recovery,
1 x Bailiff Notice of Enforcement.
All that is a symptom of an incorrect address. Have you phoned the TEC and asked for for the addresses registered with them for the Orders for Recovery? Especially the house number and the postcode.
I'd also check your driving record with the DVLA and make sure you haven't had any points added that you don't know about. You can do this online.