It might be of benefit if you contact them to find out when they sent out the Notice to Owner, as you have received a Charge Certificate, but not NtO. This would be a side-bar to the regulated enforcement process, which is that you now wait for the Order for Recovery, following their registration of the debt at the Traffic Enforcement Centre (TEC). This allows you to submit a Witness Statement that you submitted representations but did not receive a letter of rejection. This is Form TE9 and would normally be enclosed with the OfR. They can register the debt after the period for paying the CC expires, but some councils can be quite tardy.
If you can, look on TH's website at the status of your PCN. It may provide an audit trail of the status, so would show you date the NtO was produced. If you have problems with mail please tell us, because your really do need to receive that Order for Recovery. After the end of the payment period for the CC, you need to become proactive and contact TEC about 7-10 days after it expires to check on whether the PCN has been registered. If it has you can download Form TE9, fill it in and send it off, without needing to receive the OfR.