Okay, one of you is lying ....
For laughs, I decided to buy some over-the-counter birth control today. (I don't know, I saw the Sponge and got all nostalgic. I remember those from my college days ... but I date myself.) I was reading the inserts on a couple of different packages, and I noticed that each method seemed to fudge the efficacy rates to disparage the other methods. Ie., the efficacy rate the Today Sponge claims to have, is not the same as the one the Vaginal Contraceptive Film assigns to it, and vice versa.
I hate misinformation.
When in doubt, or when it matters, always consult a neutral third-party organization. Planned Parenthood gives information about various OTC options, Go Ask Alice has answered the question of effective forms of birth control, and various health sites have efficacy charts. Even the government puts out a fact sheet.
And always remember that chemical methods do not protect from STIs, so you still need that condom. No harm in doubling up methods (barrier + chemical), in my opinion, since no method is perfect.