There's actually a Simpler and cheaper method of doing this repair.
Take a normal Torx 10 Driver, available to purchase for around R 20 at most Pick and Pay Hypermarkets, then use a small ( 2mm ) flat screwdriver.
The reason a normal Torx driver does not work is due to the security pin in the middle of the bolts on the controller.
To do this the El Cheapo way, take the flat head screwdriver and wedge it into the bolt against the security pin, then apply pressure outwards.
Those little pins simply snap off.
Then use the normal Torx driver to remove the bolt
Now the contact part of the controller, the little rubber pads that sit between the button and the controller board, either take them out and clean them properly, to see if this fixes the response issue, or order n replacement set, I think Zaps has them as an import item.
Note** Breaking off the pins in no way damages the bolt itself and literally only serves to remove the 1mm pin from the bolt allowing a normal store bought Torx driver to work.