Getting a reference / review from a customer (written or video) is powerful.
The key is to have DETAILS otherwise people may think you have paid for a good review.
Too many businesses think it's too pushy to ask for a review. And it is - if you haven't delighted them. If you have, REALLY helped them in some special way, they will be happy to help you out. I know this because I've done it.
Ask them over the phone (It's more personal / effective) to email it to you.
And while you're talking ask them what one thing stood out in their experience? and record it.
Then email them saying "Hi this is my email to reply to (to make it easier for you) for the testimonial, Thank You ..."
No reply in a week, then send a pleasant email reminder with the one thing that stood out, to jog their memory.
When it arrives do not change it IN ANY WAY, even spelling mistakes. Because you want it to be their AUTHENTIC expression.
Yes it's a bit of work, but reviews are POWERFUL and they will serve you FOR LIFE