Harassment via unsolicited sms's

I am being harassed on a daily basis by FinChoice sms'ing me with regards to an account which is outstanding. This started just before Christmas - on the 20th December 2017.

I had to Google Finchoice. Don't even know who they are. I don't have any accounts on my name. I was also harassed by another debt company earlier this year for debt of a previous employee who got fired more than 2 years ago! I assume they're looking for the same person.

Please advise me on how to deal with the situation and where I can report this misconduct.