got any links for this?

I stay well clear of spread betting, you can lose a lot of cash very very quickly.

Sounds risky... 6k profit on 16.5k invested over a year is way above the odds. The fact thay they charge you £300 a month for managing your investment means that they win whether you make money or not.

They must be gearing up your investment significantly and I suspect you'll find a warning that you can lose more money than you've invested ("Your home may be at risk etc."). Check the small print regarding "margin calls" etc.

if it was consistently that easy to make 6K off 16.5K, why are they offering the opportunity to other people at 300 a month, why not cut the middleman out and just mint up themselves

I'd steer well clear.