As the weather changes from winter to summer and back to winter UPVC and composite door tend to expand and shrink causing a mis-alignment issue, particularly if the sun shines directly onto the door or window frame.
If your Upvc door handles are getting difficult to lift in order to lock the door book a Upvc / Composite door service as this is usually the first sign of a poorly aligned door, which if caught early can be rectified by a experienced locksmith meaning that the door can be re-aligned before the multi-point lock (the long strip along the edge of the door) fails which is obviously going to cost you far less than opening and replacing the multi-point lock at least 80% cheaper in most cases. The sooner the problem is rectified the less damage that will occur and the smaller the repair bill will cost.
Don't let your door locking mechanism fail leaving you on the wrong side of the door in all weathers with a large bill to open and replace the lock when the solution is simple and a far cheaper. 
We can align your door so that the door locks smoothly prolonging the life of the multi-point locking mechanism.
We are based in Diss but we cover many areas within Norfolk & Suffolk including Diss, Norwich, Ipswich, Bury St Edmund's and Thetford.