Do you have the prepaid service? The service that you activated yourself from the iPad? You can't get international roaming on that. You need to switch to the monthly, no contract plan. Then, you can get the international data plan which is $25/100 megabytes.
Or maybe they just don't like you? Without more details, it's hard to tell why they won't.
If you have the new iPad (AKA, "iPad 3) you can just get a local SIM whereever you're going and it will be much cheaper than Verizon's international roaming rates.
Oh, and it's 60 days, not 6 months that you have to be a customer in good standing.