How to fix a door bell push to uPVC door?

Since I have ha a uPVC porch installed, the door bell does not work reliably. The push is stuck to the uPVC door frame with sticky pads. Thinking that the problem had something to do with cold weather, I have replaced the batteries and the whole door bell and push twice. The last one is a weather proof door push, but it still won't work properly. I have found since, that uPVC blocks the signal and the push should be mounted to the brick wall. I am reluctant to do this, in case the bell still did not work or needed replacing in a few years time and I ended up with holes in the brick work for no good reason.

What is the correct way to mount a bell push? Would it help to mount it onto a wooden block and stick that to the uPVC door frame?