Robi Venture

I use Robi since 2004 but their speed of internet is worse than any other operators. I cant stop using Robi coz this number is known to my friends and family, otherwise I change it. I live around a area where Robi tower is only half mile away from me but I find no 3g speed. Their 3g or so called 3.5g speed is less then tortoise.. Even a tortoise can win compiting with their 3g. I find only one or two network even they are flactuated every moment. I also make complain but they do not do anythings..