Oh dear. I hope you didn't spend too much on these- it will be tough to find a matching set of heads. You can check with Bruce Sinclair at CMB Integrations to see if you can order replacements from Meridian. You will need the tops to test them as these contain the tweeter and mid-range driver.

Other options could be trying to part them out (selling the drivers, back panels and power supplies on eBay)? Not sure what else you could do. Trying to make replacement heads or hiring a cabinet maker will be a big project and likely time-consuming and expensive.

Hopefully the seller can find the heads and it will all work out for you!

Good luck!