Read your contract, do the math, go into your "adviser" and make them explain everything to you, but be careful, they will probably be lying to your face.
I would advise against this unless you're a very quick thinking, confident person who is experienced at turning down sales people.
Their whole job is to convince people to give them money, and they are generally very good at it. The average person instinctually avoids awkward situations, and they are good at creating them. They'll pick apart any argument you bring up (using numbers or assumptions you can't disprove in that moment), and in the spur of the moment they'll make you agree with them. It's only later, after you're home and signed up for another $500/month that you'll run the numbers and realize it was bullshit. There are not many people out there who are confident enough to tell someone in person "While what you're saying seems to make total sense right now, I think you're lying to me and screwing me over, I'm out." You'll feel like an asshole doing it, and they're counting on you not wanting to feel that way. It's doubly difficult if you can't prove they're lying, which due to this particular company's vague fee structure and returns promises, will be nearly impossible until it's too late.
If you run the math and it looks bad, just cancel. No need to give them a face to face or phone interaction.
edit: And to echo the above about your colleague supposedly making money, I know people who buy a house way too big for themselves, sell it for $10k more than they bought it a year or two later, and think they made $10k. They don't consider the transaction costs (>$10k), extra they paid compared to renting a place, or any of the numerous repairs they made during the years living there. People want to believe they're making money, and usually don't really run the numbers.
Your coworker may have made $3000 on this over the last 4 years. He may think that's a lot, but investing in the s&p 500 over the same time frame would've made him $5000 (assuming $500/month for 4 years). Then again, he's probably looking at what they tell him his return is, which may not include fees, or may include his contributions as part of the return. There's no telling. In any case, even a bad investor should've made money over the last 4 years. The question is, did he make more than he would've in a lower cost option?