Ovo Energy

I can't believe how many issues I have had with this company overcharging me, I'm using the same amount of electricity and gas I have always used, which isn't that much really.. and im being charged over 2 and a half grand a year?!?!?!?! Ive been paying monthly payments of £60 and just checked my account to see that they think I owe them 2 grand? I'll be switching on Monday and I will be appealing this issue with them...STEER CLEAR