Settlement letter and payment dispute

Had a term loan with Finchoice from 2018, in February 2020 I disputed their monthly installment and on the 4th of March I requested a settlement letter. Which I paid on the 4th of March. Come month end of March they deduct again from my account, I call them they say they wanted proof of payment, and I sent it. They sent me an sms saying my query have been resolved. April and May they deduct again, called them numerous times to update my status and close the account. Today they telling me because I disputed in February I'm liable to pay and m asking what was the settlement letter for, and I have been talking to them for the past 2 months nobody told me about this before. Why didn't they tell me that their settlement letter was not updated and my question is how was I to know if it was not updated and why was I not told all this time. On the 8th of May they sent me an sms saying my query has been resolved they never mention that I have to pay. This is so unfair as I have taken other financial obligations knowing that I dont owe them anymore. Please help me I'm frustrated about this thing. I don't understand why they have *********** consultants.