Just wanted to update the status here.
I finally got the chance to take the car back to Meridien this afternoon. They inspected it (and showed me too), they found that both leaks had been fixed, presumably before they got the car. It is clear that the gearbox has been resealed with fresh sealant and there is no sign of any leaking oil over the fresh sealant. The site of the original coolant leak was quite obvious, it had been fixed with a new clip and there is no sign of any crust around the clip.
I also reported to them that the rear brakes had been squealing in reverse. They inspected the pads and found they had uneven wear, leaving them wedge shaped front to back. They replaced the pads for free. No explanation as to what may have caused the uneven wear. Anyone here got any idea?
Anyway, I cannot fault Meridien's service so far.
Luke