A very common issue we encounter is a Upvc or composite door catching or rubbing on the door frame causing difficulty opening/closing the door. This becomes more apparent with a change in the temperature. We often see often 3 or 4 a week with this problem. Several issues can cause it with the main one being poorly fitted packers around the glass (it is the glass or panel that keep the door true & square), if the packing is done poorly then a few years after installation the door has dropped sufficiently to cause the locking system to no longer function smoothly or the door has started to catch on the threshold. The next common issue are the hinges, either worn or badly adjusted, sometimes the hinges have no adjustment or the adjusters have seized/broken. We would either have to replace or adjust the hinges as necessary. There are several other problems that cause the door to catch but the above are by far the most common.