I asked him how much extra money I owed them. He said he didn't know and couldn't accept my package or do anything for me if I didn't know how much the shipping that I'd paid for had cost. I told him I'd pay the difference or whatever -- an extra dollar, two, three -- but apparently that was impossible. He just kind of stood there and stared at me, about 30 seconds passed and he didn't seem to care.
Odds are the rate is the same and I don't owe them a single cent but now I'll have to wait until Monday to find out.