Once you knew their limit you should have set fire to them, not driven to another country and back on them.
I bought a car with brand new ditchfinders on it once, I almost understeered onto the other side of the road on a damp corner at moderate speed. I ordered new tyres as soon as I got home and the old ones went in the bin with 8mm of tread on them.
I find it slightly bizarre that such awful tyres are legal. Look up reviews for the Autogrip F107 for instance. They should be banned in this country. There needs to be a minimum standard.
https://www.tyrereviews.com/Tyre/Autogrip/F107.htm
You should never buy anything below a mid range tyre like a Kumho, Falken, Nexen, Uniroyal, etc.