My pensioner father recently had someone knock on his door saying they'd been doing work in the area and had spotted his roof needed repairing. This got Dad worried as he can't afford any major work, but I'm suspicious about the whole thing. What would you advise?

You're right to be wary. The approach you describe is a classic con. Rogue traders often call unannounced offering help with roofing, paving, or general building work they say needs doing, or offering to do insulation or install burglar alarms. They often end up running off with your money without ever doing the work, doing a very poor job, or doing work that never actually needed doing. Follow these top tips to avoid getting involved with a dodgy trader:

• Don't ever agree to work or sign anything on the spot - take their full details and say you'll get back to them
• Check their details - they should give you their business name and address and not just a mobile phone number. Check these to see if they are genuine
• Check if they are a member of a professional trade body, belong to a local authority assured trader scheme, or to the TrustMark scheme, which can help you find trustworthy tradesmen in your area. For more details about these schemes, go to www.direct.gov.uk
• Ask them for details of other customers they did work for and contact them to check this out
• Don't get taken in by their sales banter - they might claim there is a special offer on only for that day, or that they'll get sacked if you don't employ them. This kind of talk is likely to be a sales pitch and you shouldn't take it seriously
• Always get more than one quote before employing someone – it's usually best to contact other traders your friends or family have recommended
• Don't ever make a cash payment upfront - a reliable trader won't ask for money before doing the job - not even if they need materials. If they run a business, they should have enough money to cover these costs themselves and only ask for payment once they've completed the job, or done a reasonable amount of work
• If you think a trader is trying to con you - speak to Consumer Direct on 08454 040506. They can report anything suspicious to your local Trading Standards Department
• If the trader becomes aggressive or threatens you, this is criminal behaviour and you should call the police straight away.

For more information about your rights when getting work done, see Buying services - your rights on the Citizens Advice Adviceguide website.