If your UPVC door is difficult to lock, or hitting the frame – get it adjusted. Leaving it will end up breaking the mechanism and being unable to open your door, or unable to lock it.
Take a look at the part above and how extremely worn it is. It is part of the mechanism of a UPVC front door that eventually jammed shut. This door must have been wearing against the frame for several years. We were called to open the door and carry out repairs. Repeated strain and force required to lift the handle eventually broke the gearbox. A simple adjustment would have stopped this from happening.
Some unusual multipoint mechanisms can cost over £200 just for the part.