Expensive fly screen failed on the cat - is that a defect?

Even the screen door made of metal mesh was shredded by our 5-kilogram tomcat. Unfortunately, cats and fly screens are mutually exclusive.

Damn, the answers are unfortunately obvious O.o
That's a shame, especially because of the ground floor office where we spend a lot of time in the evenings and where it gets extremely hot when two gaming PCs are running, so we like to open a window sometimes.
So we would. But I can't stand mosquitoes, I seem to be allergic to them, when one of those little beasts bites me a single bite tends to swell up to about 20cm in diameter. :(
Cortisone, Bite-Away, I've tried everything - the only thing that reliably helps is not to get bitten.

Maybe we can re-stretch the frames ourselves? Does anyone know if that's possible?

You can hang individual magnets at cat height on cats. Then they see the fly screen better and don't have to get so annoyed.

What good is it if they see it? They will still try to climb up it.

Damn, the answers are unfortunately clear O.o
That's a shame, especially because of the ground floor office where we spend a lot of time in the evening and it gets extremely hot when two gaming PCs are running, so we like to open a window sometimes.
Well, we would. But I can't stand mosquitoes, I seem to be allergic to them; when one of those critters bites me, a single bite often swells up to 20 cm in diameter. :(
Cortisone, Bite-Away, I've tried everything - the only thing that reliably helps is not getting bitten.

There are plug-in devices for the socket that repel the bugs. Unfortunately, the ones that have helped us for years are no longer available like that. We now also have to test what works.

Maybe we can restring the frames ourselves? Does anyone know if that's possible?

That is certainly possible, however, we cannot help you with what is installed on your end and how the construction is.

With us, the patio door without a cat is covered with gauze fly screen, which has held the door for years.
With acquaintances who have cats, the door manufacturer installed stainless steel fly screen up to one meter high, just as fine-meshed as gauze.
The cats have no chance to get in with their claws.
The door has pivot hinges, the stainless steel part has dents and bumps, the cats go through the door by pushing it open.