Vericred *****sters

Currently having an issue with ampath and vericred solutions. Got billed by ampath for around R237.00. Ampath handed me over to Vericred. I settled the Ampath account. My account was settled bit I still received sms's from vericred. They managed to get through to me and said that I owe vericred money. R254.10 even after settling the bill. More than what I owed Ampath. They kept saying that I owe them interest and service fees since they kept trying to call me and send me messages. A company I never dealt with before, I now owe them money.

Ampath should've rather told me to pay vericred instead of them directly that way I wouldn't have to pay twice.

Has anyone else dealt with this? How can I pay someone that I never had any dealings with? Is this even legal?

Ref: 10001114966055.