If I'm buying passes when I get to WDW, I usually put them on my credit card vs my room charge. I just don't need that large an amount sitting there. I have been denied charging priviledges in the past due to exceeding my limit..usually at Pop!! Of course, there was the time at BC. My dh had gone to our bank, before leaving home, to make sure the daily limit was high enough to cover our end of stay expenses. Ok, no problem. However...dh left a few days before dd and I did. So, when I woke up, there was a message telling me that I had to come to the front desk and settle my bill!!! Well...long story short...dh had forgotten the we have different numbers on each of our cards...same account but different numbers (debit cards), and he hadn't had my daily amount lifted!!!!! It was at $500!!! Uh, not close to my balance!!! I called him at home, he went to the bank (thank heavens he was in town), got the limit removed. While he was at the bank, on the phone with me, I went back to the front counter, where the CM had a very snooty attitude..kind of looked like he thought I was trying to pull a fast one on him. Well..he submitted the charges again, with his eyes rolling back in his head. And yep, went through just fine. man, did his attitude change quickly!!!
But, you can just go down to the front desk during your stay and have them charge your credit card then...that will leave you with a zero balance on your room charge...which should be fine for charging.