Everything works differently in France. Sometimes the differences are obvious, and sometimes they are subtle. It's the latter that catch you out.

Take insurance. I don't much care for it, frankly - always considered it something of a con trick. But you have to have it. That's the law. We are obliged to take out building and public liability cover for our house and insurance for the car.

The car insurance has just come due and I was bracing myself for the impact on our bank balance when a friend suggested we might be able to get a better deal. The problem was, I thought we were too late.

If memory serves, the rule in France was that you had to let your insurer know at least a month before renewal if you intended to cancel the policy or move to another company. Otherwise you were committed to another year with the same insurer. Sheer indolence and a lack of awareness about renewal dates meant we've stayed with the same company for many years.

Apparently, I haven't kept up to date, because the rules seem to have changed. Even so, not everyone is playing quite fairly.

An agent for AGF - a charming young woman called Sophie - came to our house and checked through our current policies. It was only then that I realised that the car insurance was due that week. She was professionally outraged - but not surprised - to find that our current insurer had not yet sent a reminder. Because this is how it works now: the insurer sends you a notice with that year's premium. If, like us, you pay by direct debit, you need do nothing. The notice itself contains the new documents (green card and the ticket you place inside the car's windshield). However, if you're shocked into action by the size of the premium, you have 15 days from the date of issue/posting to cancel the policy.

It's that date of posting where things get tricky. Sophie told us that, when the notice arrives, we should keep the envelope.

Sure enough it came. The date of issue on the insurance document was the 6th of the month. The postmark said the 24th.

If you didn't know better, you would assume that you were simply out of time in which to cancel. Fortunately, Sophie was clued-up to these shoddy practices, which are now widespread, apparently. The postmark is the date that really matters. We signed up with AGF and she handled all the business of cancelling with the previous insurer.

It was worth doing, too. Our new house and motor policies are better than the ones we had with the previous insurer (no excess on the home policy, for instance). We also took out two life policies and the whole thing came to 100 euros less than we paid for home & motor with the other firm.

Lesson learned. We need to keep on top of these little regulations. And we have to assume that even major companies with reputations to protect are not above breaking them.