TL;DR

• SES Water had been contacting me by mobile phone semi-regularly over several months asking for a name which is not mine, but my ex partner (they do not know this). I kept telling them it's the wrong number, and eventually blocked the number.
• I've now been getting calls and texts from "UKSL" which returns as a Searches company for debt collection. I've been ignoring these outright.
• I don't believe either company knows my name or address, just the phone number.
• My credit report doesn't show that I'm financially bound to SES Water.

What recourse do they have, and do they have authority to get my name and address from the phone service provider?

Extra details:

The name they're asking for is one of my ex partner from over 5 years ago. I helped set up their water account when I lived in Surrey with them, but ensured the account was transferred to their name when we parted ways. Neither of us live in Surrey anymore.

I do have the phone number of my ex partner, as it hasn't changed from my contact list, and I could extrapolate their new address as they've still got location sharing enabled to me via their phone. I'm not sold on giving either company this information however.

I'm wondering what actions either company has against me individually, based purely on my phone number. I've had no physical letters from either, and they're not asking for my name, so I get a feeling they do not know who I am. There's potential options of me giving the contact number to who they're looking for, but could this also tie me into the debt by association?