What is the goal of the survey? Are you trying to get direct feedback from your customers to improve quality or are you trying to get reviews for marketing (website, SEO, etc.).
We had a card that we used to use and it was nice to get them back from the customers but they usually didn't tell us a whole lot. We then started to get reviews for our own website if possible by leaving a review card with a URL for the customer. It had some success.
We recently signed up with a company called Podium and it has been great. It is a software that allows techs or the office to text a review invite from their phone or desktop. All you need is the person's name and phone number (can also send to an email). People have their phones with them all the time and texting is a much better way to reach out. The software links to Google, FB, Yelp, Yellow Pages, and more and the link allows the customer to leave a 3rd party review on the top three you choose.
We started two months ago and went from 54 Google review to 119 today plus more on FB, Yelp, and our own website review portal. You can also respond directly to Google and Yelp reviews from the platform without having to sign in to each separately. It tracks how any invites are sent, who sent them, if the customer clicked the link, if they left a review, and links the sender to the review so we can pay an incentive for those getting reviews.
It also has a messenger app for texting customers which we plan to start using for maintenance reminders. Cost is very affordable.
The feedback is great but the most important thing is that potential customers get to see it. When we got a letter in the mail singing our praises it's a great feeling but it doesn't help you get other new customers.
Hope this helps
Tyler B. Kime
Standard Heating & Air Cond. Co. Inc.
Air Conditioning Contractors of America