Shocking service on complaint

I am a longstanding customer of Altech Autopage and have never found them to be inspiring in any way, but have stuck with them for convenience. In November last year I received an astromical bill for my data, which then continued the next month. I queried these statements and asked for the amount to be investigated as I firmly believe there is a problem somewhere. In the 2.5 months since I started the process I have had nothing but incorrect feedback