Broken zips!

I haven't used one of those, but I use a small stapler and it has worked.

If the break was right at the bottom I used to snip horizontally just below good teeth into the side without the pull bit (probably has proper name lol) and then slide that piece back onto the teeth. Then sew across the broken part closing the cut at same time. Hard to describe but hope that makes sense.
I rarely have anything with zips now.

dirgni I have not tried the instant fix but I do wish they where available years ago because I have lost count of the amount of items I have discarded because of broken zips and as you say it is so expensive to have new ones fitted.

Get a sewing machine, go on a zip replacement course and do it yourself. I have never thrown any clothing away because the zip was broken.

I am not a brilliant sewist, nor have I yet done the course but I will be signing up for it as I am struggling with replacing a zip in an expensive anorak. But throw away a jacket that cost about £100, 7 years ago because the zip is broken - Never!