Hello all, First post here! I've got some Patiomaster doors which I've had a fair amount of trouble with since their installation in 2017. They've been adjusted multiple times - despite this, they bow in the middle (gap is smaller than at top and bottom). They've recently been adjusted again by the installers (who have been very accommodating) who have bonded the glass to the frame + used packing material (or something similar - I'm no expert) but the problem continues to persist. Is this a known issue with UPVC patio doors? If so, can it be remedied? If it's not a known issue, does anyone have suggestions around what to do next? The installer is FENSA registered so the doors come with a 10 year guarantee.