Sadly, many of us are not lucky enough to have a photographic memory. There aren't a lot of people who would remember what they had for dinner last Monday. For this reason, customer satisfaction surveys are usually done while the service that was provided is still top of mind.
If you are in charge of running a customer survey go straight to the source. If it's a restaurant, have surveyors outside asking customers for their thoughts. You can also hand out survey sheets instead of live interviewing. Whatever you decide, just make sure you administer the survey sooner rather than later so the customer doesn't forget.