Tektro RL 340 brake levers cannot find tightening bolt to keep shifter secure I have this bike from Decathlon, but the right shifter started to come loose and drop down, so I have unwound the bar tape and proceeded to move it back up. 

But unlike my old shifters there is no bolt to tighten it up! I have looked everywhere on it, but cannot see it, it seems that is only held in securely by the bar tape. Is there a way to make this more secure? As at the moment it is still moving around.

It has Tektro RL 340 brake levers, not sure if I am doing something wrong.
The brake levers are held in place by a metal band that wraps around the bars. The band is tightened with a bolt inside the brake lever. One may see the head of the bolt when pulling the brake lever and looking into the gap between hoods and lever.

A L-shaped hex key should easily reach it. The brake cable might be in the way though. By slackening or usinga ball-head hex key one may adjust that bolt without removing the brake cable.