Excellent advice about asking. I also usually confirm point balances for the current and next use year after every transaction. In fact, the MS rep usually confirms that information w/me without my asking.
I always double check, too - tracking banked points and "new" points separately, that way when the CM says how many points I have left I can always confirm my number and type of points - if I have 75 pts left, I might ask if that includes my 100 banked points - the CM has always been able to tell me my banked points were used.
Another thing to do is to be online and logged into your "my DVC account" when you are talking to MS. I have noticed that often your transaction will show up immediately, and if you do a refresh, you can check it right away.