Why was my line suspended while roaming? What is the spending limit?

It sounds like you may have reached the cap for Easy Roam depending on which country you’re in, though I don’t think this would terminate your phone service.

“For U.S. destinations, the $14/day fee is capped at a cost of $280 within a bill cycle. For international destinations, the $16/fee is capped at a cost of $320 within a bill cycle.”

Have you missed any bill payments prior to April 11?

To view your payment history, first log in to Self Serve. From the Self Serve dropdown menu, select Billing, then select Account history.

Payment options for overdue fees

I believe you would have to pay the full amount owed.

“Once we’ve received your payment arrangement online, we’ll restore your service quickly (typically within an hour). Make sure you turn your phone off and on again to reactivate your service. A reconnection fee of $50 will be applied to your next bill.”

You mentioned that "  I just presuming I’ve just maxed out my “Koodo credit limit”."

Do you mean by are you on the spending limit plan? If so, you needed to pay the amount that went over the limit even before the billing cycle.  If they disconnected, then I believe you might need to pay whole amount and reconnection fee. 

Since you are outside of Canada, you can send them a message through FB or Twitter to ask them make some kind of arrangement...