Greetings!
You might curse them so that if they reincarnate they would suffer. 360+ probably or several years (360 days cycles) of normal runic curse with the affirmation of what is just for them to go through. For example if they did something to others they should experience it on their own skin, so affirmation might be "they receive every and all evil they did to others" (with corresponding details).
Honestly I do not yet know how to control soul reincarnation process, but I strongly believe this is possible and science of the Earth soon will come to it. You definitely should ask Gods for these type of Technics when you are ready to hear or somehow feel their response. I believe there are endless technics that are known to the advanced people here but are not openly put into ToZ website. Simply because they are endlessly mentioned in the Ancient texts even in their translated version. Also there might be methods of torture after death that we do not know about.
I do not think this is "extreme punishment" because no soul = no sufferings. Probably if they are evil they deserve to reincarnate to go through this evil instead, not that easily die and get away with it. It is just too easy for them. People usually do too much evil to just dissolve on the astral and get away with it like that. Even before dissolving they should go through Tartar or related experience - to know what they have done to others.
But some people waste their soul matter for too long and they die anyway, so probably your enemy will at some point die on its own.
Anyway I think, since dying is too easy way out, you should focus on the rightful punishment rather then on controlling soul reincarnation process. Unless your goal is to investigate into the reincarnation process itself for pure scientific purposes (in the ethical way).