HI Esther,
We are sorry for the delay but they had a day off yesterday and today there are a lot of unprocessed customizations requests.
They will surely reply in a day or so but
Since the booking feature is a custom one and it works with WooCommerce plugin, we cannot speak about replacing it with plugin because it will simply don’t work.
You will either need to choose a solution to build the booking feature from scratch or develop the existing one. Both solutions are quite expensive in implementation.
Unfortunately, I cannot provide you with a realistic quote for this work but if speaking with approximation I can tell you that this project will cost you $1000+ or maybe much more.
Best Regards