Having been on a Three sim contract for a while myself they regularly ring me and talk me through their deals. They did again yesterday and because I happened to be looking for a new deal this time I picked up a Galaxy S9 with no upfront cost on 12gb data, unlimited everything else, go binge and free Netflix for a year (saving me 7.99 a month). They dropped the price a couple of times after I said no and removed the upfront cost of £79 and ended up agreeing to £44 per month, so it is worth persisting with them. There are some cheaper deals out there on other networks but not giving me things I actually use like Netflix.