Question: Gas and electric: could there be a setting on in my house that’s causing my bills to be so high?

Since my flatmate moved out, it’s been just me here… The energy use has gone down, but my gas and electric bill prices have gone up? Could he of set something on the gas or electric metres, or anything else to make the cost much higher? He was a horrible person, and left bitter because I wouldn’t pay his half of the bills for him, so he could stay at home all day smoking dope and “working” 2 hours a week..