4G LTE Data Slow on AT&T Network 2015 and 2016.

I have raised 5 cases with AT&T in regards to slow data on the LTE network. I have gotten to know that my area has at least 20 towers but these are saturated with customers. AT&T cannot provide a resolution on this matter except to switch to 4G which eventually slows down too. I do not have an unlimited plan that slows down after 5GB and I have the latest iphone and software. I've done speed tests with people than run other networks that rent from AT&T and their data goes faster than mine. Family, friends and co-workers have the same issue. Why would you rent or bring in new customer to your network if you can't handle the load for your existing? I'm very frustrated with your company.