If the notice of rejection was lost in the post, there is no guarantee this won't happen for the order for recovery as well. If you miss the order for recovery, it can be hard to impossible to get things back on track, so you can't run that risk.
The PCN is sat at £195 at the moment, keep an eye on
https://www.harrow.gov.uk/parking-permits and as soon as it goes up to £204, you can download
form PE3, fill it in (remember the applicant is the council, not you) and tick the box to say you never got the Notice of Rejection (do
not fill in the reasons box, this must be left blank), then make an appointment with your local county court or magistrates' court to get it sworn.
Once the form has been sworn, scan or photograph it and email it to tec@justice.gov.uk with the PCN number in the subject line.
When the amount due on the council website drops back down to £130, it means TEC has served a revoking order on the council. Let us know when this happens (you'll need to check once every 10 days or so after you've emailed TEC) and we'll help with the next steps.
Any questions please ask.