Shower drain too high, therefore ground down, now there is a hole

Hello, our shower drain was installed too high. Unfortunately, we don't have an invoice for the work. We thought about it back and forth and then decided to grind down the drain. Now a big problem has occurred. The drain was double-walled and we have ground down so far that the drain now has a gap. Of course, we didn't know the drain was double-walled.

Please no comments like "your fault for no invoice," etc. We are already beating ourselves up enough!

Of course, the worst case would be to remove all tiles and the drain and redo everything.

Do you have any other ideas? Can the drain be sealed again? It is made of stainless steel. We have thought about soldering it?

To do it with glue and then cover it with silicone.

Do it with glue and then cover it with silicone.

That’s just botching it as well.
You can’t solder it, maybe have it welded, but then it’s too expensive again.
The only technically correct way is to remove it and replace it completely.

That's just botched work. You can't solder that, maybe have it welded, but then you're back to it being too high. The only technically correct way would be to remove it and replace it.

What do you expect when someone is hacking at a stainless steel shower drain??

If welding at all, but a part like that costs less than €100. I would have installed the thing new.

The gutter is already ordered. That's probably the smallest thing. But doing everything new will easily cost four figures. That does hurt me a bit. The money isn't so easy to come by after building the house.