Does YouGov ever pay out for surveys or is it a sham?

I have been filling in surveys for about four years but am still no closer to the elusive £50 it promisesI have been completing YouGov surveys for what feels like years, hoping that I might eventually make some money out of it. There are no details on my profile but I would guess it must be about four years. Surveys used to come in every week, then they slowed down. Now I get one every two weeks and every second or third is a prize draw, so a waste of my time. The surveys take about 15 min