Saya recoveries communication charges are not making sense

I have a finchoice account handed over to Saya recoveries, the guy that called me told me I owe 2800.00 and if I settle I can pay 2500.00. I told him I Wil pay 500 monthly till I am done. I have received a call this morning, meaning it's the second time speaking to them, however I have been charged letter and call fees for more than 15 times. My question is, if you are charging for a call, do you not need for someone to answer the call in order for you to charge? Sms was only received yesterday telling me of the balance. If I've only spoken to u guys twice and only received an email once, why are you cooking charges and adding up on something I have arranged to pay for. There's also a commission fee that I am charged. Unfortunately I'm not looking for an apology, I need you to explain to me what law allows you to cook the amount so much, if possible can you explain that law or policy, I need clarity. If I'm not afforded the clarity, can you then explain to the ombudsman, cfdc and the ncr?