I've paid 1.5% transaction fee just now instead 0.5% that my wallet was configured. Was sending 0.2 and fee was set for 0.001 but paid 0.003 instead. I have 0.3.24 client.
1. Why my config was ignored?
2. Don't you think that 1.5% is not so competitive?
3. How can I enforce my fees in future?
Change your fee back to the default 0.0005 (or something else). Make sure you are running the current release of Bitcoin. Better yet, set the fee to 0, and then Bitcoin will send your transactions with no fee, and prompt you if you create a transaction that actually needs a fee.
Stop getting tiny mining payouts. These increase the size of your transaction when you spend them, increasing the fees you must pay.