I need a wix developer

Hi guys, I manage a weekly farmers market. Thanks to coronavirus, the farmers market has been suspended and all my small farms and vendors have lost their income and their way to get in front of customers. So I created a website on wix [login to view URL] to offer pre-order and delivery services. I need to add a processing fee to checkout of $1.99 so I can continue doing this for my vendors. This money covers the cc processing fees that apply to delivery rates and any refunds, and keeps those fees from coming out of my own pocket. Currently the only way to do this is to set shipping rules and add $1.99 "handling fee" to the $6.00 delivery fee, which comes up as "Shipping" in the customer's cart and only shows a $7.99 total. That works fine, EXCEPT, now customers are coming back and trying to make a second purchase to the same delivery location before their Saturday delivery and I don't want to charge them the $6.00 delivery fee twice to make one trip to the same house. However, the $1.99 processing fee needs to remain. If I create a free shipping coupon, it removes the handling fee as well. If I set up a flat rate coupon for them for $6.00 and the customer only wants to add a bundle of cilantro to their order for $1.00, the coupon ONLY takes $1.00 off the order because it doesn't apply to shipping fee, only the order subtotal. So any customer placing a second order with products totalling less than $6.00 does not receive the full $6.00 coupon which is meant to offset the delivery rate. I have called Wix a few times but they have no way to help me with any of this. Next week we will be offering a pick up location. I will still need the $1.99 to apply to pickup orders, but will need to remove the $6 delivery fee. My vendors are really important to me, I have worked with most of them for 11 years, but I can not afford to work on this for 60 hours a week, forgo my regular work AND lose money on cc processing fees for refunds or delivery services. Does someone have a way to build in the $1.99 processing fee as a separate line item in the cart? Then I could just issue free shipping coupons for pickup or second orders. Accounting would be much cleaner as well. Pretty desperate over here. Thanks in advance! Brittany 772.321.7952 farmersmarketdropoff@[login to view URL]