I have severely burnt by laser hair removal. What would you recommend to remove the scars?

Without pictures, I can't fully advise you.  However, it appears you have 2nd degree burns which can form caring and pigmentary issues.  I'm sorry this happened.  The black eyeliner will attract the laser and could have been the problem or the laser settings were not appropriate.  I do all the laser procedures myself and that seems to be the exception and not the rule with hair removal.  It seems like such an easy procedure, but when things go wrong, permanent problems can result.  Biafene, applied liberal, it great to help burns heal.  You might need antibiotics or Silvadene too.  Sometimes, hyperbaric oxygen can speed recovery.  Please see a Plastic Surgeon to help you through this.  Steve Weiner, Facial Plastic Surgeon.

Without a photo, a difinitive diagnosis is difficult, however it sounds
like the burns are pretty severe. You may need to see your doctor and
get an antibiotic. The laser picks up pigment so putting black eyeliner
on your body wasnt wise. Laser settings need to be changed to take into
account skin tone, if the client is tanning, etc. As far as the "scars"
go, you cant really treat those until your skin has healed.

Lasers and IPL are attracted to color. So if you mark an area with a black marker or a skin marker, the machine is going to hard target those areas and burn them. Any knowledgeable technician would know this.... To properly mark an area you have to use a white eyeliner. That is the only acceptable color. You need to seek assistance from a physician immediately for post wound care and prescriptions. Hopefully you will not have long-term lines and damage, but I wouldn't count on that.... Your technician absolutely should have known better than this and I would not recommend returning there. "This answer has been solicited without seeing this patient and
cannot be held as true medical advice, but only opinion. Seek in-person
treatment with a trained medical professional for appropriate care."