We did the sons Vectra last year, three broken springs, replaced all four obviously.
I bought a cheap, £15, eBay set of spring compressors, they only just did the job, the threaded bar was wearing as we tightened up the spring.
I've done a few over the years, they still scare me to death, it's like handling nitroglycerin.
A bloke on another forum told a tale of his mate being a bit "matter of fact" replacing a spring. You know what happened next, one of the spring compressors went through his garage door.
Respect the spring.