Call them ask 4 help
Look for a box to check allowing you to enter a different address from billing.
Your best bet is to give him a call normally there's internal procedures and standard operations that they need to follow. Although there reps should be trained to explain and help resolve the issue.
Most companies have policy on online orders that the billing address is the same as the shipping. Using a prepaid card online is a way around this.
Thanks! Your answer is awaiting moderation.