appointment payments

[Newbiehere]

I started using square appointments to have clients book their own appointments. I have a policy to hold a deposit on the card as a cancellation policy/to prevent no-shows.

I have had several clients attempt to book and they are either unable to book, citing declines on the site despite entering correct information.  Or their cards are declined when i go to process their payments for similar reasons.  I have concerns with this because 1) clients will go elsewhere for services if they can't easily book appointments and this has happened; 2) the entire point of having a card on hold is to decrease cancellations and no shows. If I cannot see that their cards are not going to process for some reason until the day of their appointment then the purpose has been defeated as a declined card for a no show does not help me.

I called square support and their only solution was to require prepayments of the appointment instead of just a deposit.  Why is this the alternative if you offer a deposit option?  Why can't they just fix the option to check the client's info prior to the visit so we can ensure that the card works?   Also, not all of my clients will have upfront costs. 

If this can't be resolved I will have to choose another processor such as stripe or try Hubspot to get what  I need.  Any tips on how to make square work or better alternatives for appointment booking with payments and reminders would  be appreciated.

A link for testing: https://squareup.com/appointments/book/lddircavq5h2av/L7YD5947MZKYC/services