Unacceptable design and construction of oven

In October 2024 I bought a 600mm Defy Slimline oven which has been a problem since it was first used. Their field technician has done all he can to resolve the problems, but with limited success. A defective door seal directed very hot air onto the adjacent kitchen unit and burnt it. The seal was replaced, at which time the technician found that the door's hinge on that side had not been installed correctly, so he replaced it and fitted a new door. That improved the situation, but another problem which is a safety issue remains unresolved. The oven has a removable inner glass window that is removable for ease of cleaning. It is held in place by a clip-in moulding at the top which becomes loose when the oven is hot and releases the top of the glass. The original moulding has been replaced twice, most recently with an updated design, and it still release the glass when the oven is hot. We are pensioners and my wife bakes to help us financially, so the stove is unacceptable in its present form. My wife has used defy appliances for many years and this is a huge disappointment. We are seriously considering getting rid of this oven and buying one that is more robust.