Truworths harassment and emotional distress

sometime last year I helped my grandmother open an account and it was successful, unfortunately she skipped about 2 months payments due to unforeseen medical expenses, later on they called and we made payment arrangement and only to find out they called 2 other family members who were not listed as contacts and they got concerned because they were not aware of the account and that caused a fight, I then took it upon myself to call Truworths asking that they remove their information as we never listed those people as contacts, but that never happed cause Truworths is now sending them texts regarding the account emphasizing the account areas, I need Truworths to stop this, I'm the only contact they should interact with, it's causing destress to me grandmother as she's frail and it's depressing me a lot, especially given the fact that I'm batling serious mental illness.