Barmaid - out of interest, which is the utility company, and what, roughly, is the problem? In the past few years by writing concise, clearly worded letters of complaint I've had a resolution of problems and apologies from Npower (twice, both times with £50 of the next bill) and Severn Trent, again with £50 off the next bill.
I think the key is to keep it civil - though strongly worded- clearly state the facts and set out exactly what you want the outcome to be. Don't let them win, and do not give up! Good luck.