Skoda Octavia 2.0 TFSI Estate 2011 vibrations from the floor

Hi All,

I have my Skoda Octavia VRs which suffers from vibration in the floor. I can fell vibration between 70-85mph under my feet. It happened irregularly and sometimes I can slightly fell them on the steering wheels but not always. 

I had balance on wheels done, alloys checked, engine mounts replaced, wheels swapped - a bit better after that but the issue persists.

Did you experience anything like it?

I would be grateful for advice as I completely do not know what else to check.

Many thanks

Yaro