Cannot resolve a simple account transfer

Since the beginning of the year 2015 I have switched over from a sleuth tracking unit to a early warning unit. The accounts department has been charging me for the sleuth unit since January in stead of the early warning unit but sending me a bill for the early warning unit showing no payment. I have been trying to no avail to get someone competent enough to realise that they are still billing me on the old unit account and that the debit order should be amended. They simple can not get this right. I did after 3 month get someone who understood the issue and was promised it would be resolved, but the problem is still there. I cannot get hold of anyone to help me with this issue and Altech Netstar has given me up to debt collecting even though I have been paying my bill each month. This is so frustrating that I would really like to pay the extra amount for the early warning unit by it seems that Altech is making so much money that they don't want the extra money.