All VM services are over provisioned to ensure you can achieve advertised speed. As an example, the 350mbit service is provisioned at 402mbits so you can get 350mbits.
I consistently get 378mbits in my speed tests and that translates to ~43MB/sec in real world downloads so if you are getting 26MB/sec it isn't good enough.
As roughbeast said, has it always been like this or have you been able to achieve max speed previously? When you do a speed test you are doing it for a specific diagnostic reason and you should always use VM's test servers wherever the closest one is to you. VM's servers are sat on their network so if you can't achieve full speed on your isp's network then there is no chance you are going to get it when you leave and go to a third party server where links outside the network can impact performance. Before we make any further suggestions can you run a test at speedtest.net and post the results. Do it in the morning and not in the evening.