There is a major difference between MB/s and Mb/s and that is where the mistake has been made. For example 200Mb/s is equal to 20MB/s. One is Megabytes, the other Megabits.
Try the test using a site other than the one provided by your carrier. While testing the speed of my cable I found a lot of variance from one test site to another. Of course, the one operated by my supplier showed the fastest results.
Comments
Where did you get the 26% increase. I found no references to individual phone speeds on their website.