Replacement Lock Handles for ARB Mk 3 Canopy

Hi all, first time poster here....

I have recently purchased a second hand ARB canopy which my research tells me is a Mk3 model.
It has the circular locking handles on it. I believe they are called a D Type lock.

Both of the rear lift up door locks have failed (cracked plastic parts that when I gently undid them to investigate fell apart in my hand). They are stuffed.

I can't seem to locate any one that sells them. I will be calling ARB in the morning to see if they stock them, as they don't appear to have a spare parts listing that I can find...

Do I have any other options for locking handles or will a Mk3 only take the circular locking mechanisms?

Have tried evilbay and gumtree as I'm waiting for the shops to open tomorrow due to todays public holiday. No luck. Heaps of T Bar handles but they seem to need holes drilled in the glass to mount the assembly according to the pics...

What options do I have to fix my rear window locks, and any ideas on what I should be paying for them? Should I fix all 6 locks at once?(the side windows are both lift ups too).

Any advice is greatly appreciated.

Kind regards,

C.A.