Is power of attorny a solution to my father's finances?

Every week a Guardian Money reader submits a question, and it's up to you to help him or her out – a selection of the best answers will appear in Saturday's paper. This week's question My 88-year-old father has always been in control of his finances, but things are starting to slip and bills have been left unpaid. At what point should I step in and help – if at all? I've heard power of attorny can be a nightmare to set up/run. Is that right? Anyone got any good advice? What are your thoughts?