It seems the maxi cosines car capsule is the online that actually fits onto the Donkey frame. And the maxi cosis have been recalled and who knows when they will be available again.
I think you're right about the Maxi Cosi being the only capsule that fits. But I hadn't heard anything about a recall? Can you tell me a bit about it, I'm a bit worried now cos we have one...

ETA:

I just found this after googling, it seems the recall was quite awhile ago and a different model to what they sell here in Australia. The one that I've got (and I'm pretty sure it's the only model that meets Aus regs) is the Titan

Maxi Cosi Mico Infant Car Seats
July 24, 2009 - More than 28,000 Maxi Cosi Mico infant car seats are recalled because it's difficult to attach the car seat to the base. If the car seat is improperly mounted to the base, the child could be injured in a crash. This recall includes Maxi Cosi Mico models 22-371 and 22-372, and Maxi-Cosi Mico infant car seat system - base only, model 22-515, produced from July 2007 through February 17, 2008. Call 877-657-9546 for a free replacement base.