You would seem to have also posted this on our Facebook site. Advice is as per I put there, namely to submit your Witness Statement before 10th April, the deadline of the Order for Recovery you have received. All you need to is tick the box for "I did not receive the PCN", no need for anything in the Reasons box.
The WS will get you back to the PCN stage, at which point you can pay or submit representations.
