Credit due

Why is it when ADT Owe you money you have to lodge a complaint on hello Peter to actually get a response.... I cancelled my ADT about 2 years ago and they owed me money but then after my complaint they paid me twice so I paid them off, but now I have overpaid them as when ever I requested a statement they could never send me one.... I have now been trying to get this sorted out since January 2015 ( I know its not a long time but I now the accounts refund department take forever) I have called numerous times and am supposed to sort it out with a Ranjay who is NEVER available...It's not millions or thousands they owe but customer service is terrible.