For customer satisfaction, we look at repeat business.... we considered that if the customer is coming back, they must be satisfied.
so annually we review sales and determine a percentage of customers that ordered this year, ordered more than once this year, ordered this year and last year and ordered every year.... (some customers only order 1/year, but they order every year.... for that product....).
we then compare the stats from one year to the next.
You can then also dive down into which customers are re-ordering, who is not re-ordering, why.... is it a sectorial issue or is it a customer issue / sales person issue..... what is happening with new customers from last year, did they place an order this year or not.....
As well, quarterly we tally any positive and negative customer feedback collected during phone calls or emails with our customers. This is more informal, so we can either print out emails (as 'evidence') or we have a customer satisfaction form that we can fill out if it is verbal. We have included suggested questions to ask the customers (quality of product, on-time delivery, website ease of use, would the order from us again....). This is less useful to us, but provides information for the auditor (which is not a great way to do something, but seems to be needed... for us the repeat business is really what we delve into and discuss).