Hi @SouLLondon ,
Thank you for reaching out, and I’m sorry to hear about this issue. I understand it is very important to resolve this as quickly as possible.
Now, to provide the best advice possible, you need to share more information on the case. Does this happen to customers directly while adding their address on shipping section of the online checkout? Or does this happen to you when you manually add their addresses to draft orders?
If you have an example or a screenshot showing the issue and/or error message, that would be very helpful in further troubleshooting.