Client not adhering to timeline

I’m wondering if anyone has advice in how to deal with this client issue.
I sent the client their website for approval and asked that they make a list of any revisions they need within 10 days. It’s been over 2 weeks and I still have not received this list from them despite a friendly reminder to please send it. At this point, it’s really inconveniencing me as I would like to wrap up this job and move onto other things.
What would you do if client is not keeping to the timeline? Charge an extra fee to make changes past a certain date? What else can I do to get them to realize they need to make this a priority?
(I don’t think they are ignoring on purpose… they told me they are just so busy etc… However, it is not fair to me that they are pushing this to a back burner and messing with my schedule.)
Any advice appreciated!

Deadlines are good for them too. I charge per hour after the deadline. Maybe extend the deadline a bit longer and tell after that you will have to charge