Harassment!!!

Sometime this year my medical aid ran out of funds and Lancet Lab was not paid in full. Upon hearing about this I contacted Lancet Lab & made arrangements with them to pay them every month, true to my word I have kept my end of the deal and paying them without fail every month. But Lancet keeps harassing me for payments, last week I got an sms to say my account had been handed over to Bayhack Landau for collections, I then called and spoke to Werner who said this was an error on their side as this acc was on agreement and not supposed to be handed over. Today just now I just got a call from Bayhack Landau demanding payment of this account. I then called again Lancet Lab and spoke to Tia who also said its an error and she will need to send yet again an escalation to her team leader or manager to place this account on hold. Clearly Lancet Lab, you guys don`t keep your promises I mean how am I now handed over when there is an agreement in place and your records show this?? How must I be harassed every single day of my life when we have an agreement in place????? Please sort your bad systems out & lets keep to the agreement as I have been keeping my end of the deal you do the same please!!! If you guys have no work to do than to harass me all day everyday I can think of a million things for you to do!!!!!!!!!