You didn't say whether you've tried reaching out to Bandai, so please forgive me when I suggest it, if you already have. That's what I would do-look online for contact info and try reaching the company. If that fails, I'd try asking the vendor, if possible. If you bought the kit from a vendor, whether bricks-and-mortar or online, he might be able to go through his supplier and provide you with contact info, or to order parts.
I hope that helps in some way!
Best regards,
Brad