Handed over even after a payment arrangement was made and recieved in writing from Fedhealth

Fedhealth(Simphiwe Malaudzi) allowed me to make a payment arrangement with them as follows for monies I owed to them: Dear Miss Loonat,Thank you for email Please be advised management has approved a payment arrangement of up to 12 months. Excess Savings: R -4,029.81 Repayments for 12 months: R335.81 per month,Regards Simphiwe Mulaudzi , which I have been paying each month on time, since December 2018, till now, and then I get the following sms today: "Please contact Simphiwe at Fedhealth on ***, as your membership has been handed over to Trans Union ITC for the amount of R1893.81 ,If I must get handed over to Tans Union for the above payment arrangement I made with Fedhealth then Fedhealth will be in big trouble. Simphiwe better sort his story out, I am warning him and Fedhealth