Here’s how I learnt to change a uPVC door lock in a minute. You really don’t need a locksmith for this and it will save you money!
How to Change a UPVC Door Lock
The first thing you'll need to do is unscrew the long screw at the side of the door with a combi drill
This unlocks the lock barrel.
Store the screw safe somewhere as you'll need to put it back shortly.
Now you need to straighten the lock barrel latch to pull out.
To do this, twist the key while pulling. It'll need a bit of a wiggle until you know it's not protruding. But don't force it if it doesn't come out - just wiggle more instead.
Now repeat the same method in reverse.
In the pic above, you can see the lock barrel latch isn't protruding - also, you'll need to see which way slots in where the barrel doesn't protrude too much. In our case, the shorter bit faced inside the door.
Tip: You'll need to measure the depth of your door including handles to avoid your lock protruding too much. Some say between 2mm and 5mm longer is acceptable, otherwise thieves can snap your lock.
Slot the new lock barrel in and twist the key until it's trapped.
Screw back the long screw again with a combi drill until tight.
Now test the lock to see if it locks ok, which is should and you're done!
Here's the one I changed at home shortly after!