Unlink my phone number from old apple ID

First time I used an apple phone was in 2014 for a period of 2 months. I had registered my phone number then with some icloud id and an email i dont even remember. Its nearly 8 years now, I finally moved into a fully integrated apple environment. Imagine my surprise when I found out i couldnt use imessages or facetime using my phone number!? Why? Cuz its linked to my old icloud account. I don’t remember the id or the email address. I use this phone no even now. I asked apple support to either send an sms or security verification or atleast tell me the old apple id so i can unlink it. Is there any solution to this or has Apple completely overlooked this scenario?