What is wrong with this picture?

hi i have a quiry my mum has a semi detached house and is paying far to much on gas and electric she has both meter prepayment and is puting in about 100 each a fortnight i told her that was far to much as i onlyuse about a fifer a week she tryed phoning the company but they alway put the phone down on her what is the best thing to do about this ?????????????