Exploiting Patients!!!!

I have been to Hillcrest hospital with my son, who needed a procedure done by one of the specialist at the hospital. Firstly, we were not advised that we needed to pay the doctor and the hospital two seperate fees. We then started receiving bills from the hospital demanding payment. The account was then handed over to a useless and unprofessional debt collecting company who is now exploiting us. I received a call from colmed a few weeks back giving me a settlement balance, which was less than the hospital amount, which I made aware to the consultant. She then advised that there is no other outstanding balances and that is the only amount I need to pay. I agreed and paid that amount. I then received a call a few days later with another amount stating that this figure is also outstanding and needs to be paid. I explained my conversation to this consultant and she apologized and said these are the only 2 amounts that are outstanding and I have her all our cell numbers to ensure that there is no other amounts outstanding. She confirmed that there are no other amounts outstanding and I agreed to pay. A few days later, I received another call from another consultant stating I have another amount outstanding. They then send me a statement and charge me for the statement which I did not ask them for. The amounts owed to colmed is double that of the actual hospital bill. To my understanding, a debt collection company charges the company to whom they are rendering a service and not the client to pay their fees. I'm sick of these money hounders just looking to exploit patients even through the difficult times we are now experiencing. Please advise on a way forward to take this up.