OP, pl get your skates on. 2 weeks have been lost so far and if you do not make representations 'in time' they may be disregarded.
But what exactly is in time for reps or payment is unclear on the face of this PCN*. Procedural improprieties seem to abound, but we can get to these once you've requested the DVD and enforcement is put on hold.
*- if the PCN consists of 4 pages, then where do the red-bannered items come from on what appears to be page 5. These totally contradict what's in the body of the PCN.
For example:
You have 21 days from the date this PCN was served to pay the discount. No you don't, you have 21 days beginning on the date of service as stated on page 1.
If you pay after 21 days but before the end of 28 days beginning with the date of service you must pay £160. No, you may pay £160 at any time after the discount has lapsed and before a Charge Cert is served.
While on page 4 we have this howler:
Your representation may be disregarded if it is received more than 28 days after service of this notice. No, reps may be disregarded if not made within the 28-day period which begins ON the date of service, not AFTER.