Freezing to kill yeast

I need to kill my yeast to avoid bottle bombs. I don't want to use sugar substitutes and I'm making a homebrewed soda which needs to be sweet.
I've tried pasteurizing in the bottle in a very aggressive manner but there was still a 5% failure rate. I've tried boiling the whole lot prior to bottling and there were still an unacceptable number of failures.
My last resort would be to filter it but that would lose some of the flavor. (racking off sediment resulted in a lighter flavor but some yeast still survived.)

So now I'm looking at freezing in the hope that slow, casual freezing in a crappy home freezer will result in large ice crystals that are going to tear the yeast up from the inside.

Any ideas, experience or feedback?

Wait, you want to freeze glass in order to avoid bottle bombs? Or are you talking about bulk freezing? Slow freezing doesn't kill 100% of yeast, but it's definitely annoying trying to get yeast from ****ty frozen stocks, so you might be OK, but don't assume that you will get 100% kill rate.

Freezing would destroy the carbonation as well as the bottles. Pasteurization should work reliably. What was your process?

Try running the capped bottles through the dishwater. This has always been a solid method for me.

Sorry I didn't want to post a wall of text and tried to only post the pertinent information but ended up cropping off some crucial info.

I was conditioning and pasteurizing in the bottle but due to exploding bottles, I gave that up.

My method was to put about 40 bottles into a big plastic tub, bring 50 litres of water to a roiling boil, pour it over the bottles, then cover it with a polystyrene foam lid which had reflective foil on the underside. I was measuring the temperature in the corner (I figure it'd be the coldest spot) and it was over 90 deg Celsius for the first 10 minutes. After about 15 minutes it reached 80 deg, so I pumped out the water with a little water pump and threw another 50 litres of water over it. So the bottles were over 80 degrees, and much of the time over 90 degrees Celsius for more than half an hour.
To make sure the cores of the bottles were getting hot, I took a bottle out after 30 mins, let it cool off a little, very carefully uncapped it, and dropped a thermometer in there and it was 85. But there were still ones that exploded after 2 months.

Lately I've been making the brewed flavouring (in this case, ginger beer) without any added water, like a concentrate, bringing it to a roiling boil, boiling for 3 minutes, (it still tastes alright after 3) then adding it to a corny full of carbonated water, which was also boiled before kegging, followed by bottling.

However, bottling after that still results in some bottles continuing to brew.

So I was thinking if I were to freeze the concentrate for 48h then do the boil after it thawed I might be able to get rid of all the yeast.

The yeast I'm using is a proper ginger beer plant. Of course I'm removing the grains before any of the kegging or bottling begins, but it's the free-floating planktonic yeast causing the problems, it seems.
Someone suggested to me that I was killing the yeast but it might have gotten stressed out and dropped spores which could survive boiling?

Try sorbate.

So I understand a proper ginger beer plant is a symbiotic relationship between Saccharomyces florentinus and the bacterium Lactobacillus hilgardii. Perhaps Lactobacillus is the issue. Lactobacillus is known to form a biofilm which can be more heat resistant compared to the platonic state. However heat should work if held at a high enough temp for a long enough period. Perhaps there was a cooler spot within your system. Can you circulate the hot water? The dishwasher suggestion may also work. I don't think freezing will. If you are not interested in the lacto tang, try just brewer's yeast.