Shopify wholesale customers have trouble ordering often

[JASON-BMS]

I have this reoccurring problem that’s lasted for years and is like groundhogs day over and over with my Shopify wholesale customers. Everything is fine then all of a sudden no matter what they do they can not order and get vague error codes like “this transaction cannot be processed”. They restart their browsers and computers, try other browsers, phones, devices, credit cards, IP addresses, call the financial institutions to no avail. They have placed many orders in the past but one day they just can’t order anymore from our Shopify wholesale side. We eventually send them to our Shopify retail site and they can order fine 100% of the time then we have to go refund them the % off for the wholesale price, sometimes on 40+ products. The wholesale discount is different for all products so we have to do each product individually which is not ideal. This upsets my customers and my employees. Any idea how to get this to stop once and for all? It’s something Shopify-related. Retail side always works well. I have spent many hours explaining this to Shopify support over the years and the problem will just fix itself eventually and then the next week another wholesale customer cant order. Any advice would be appreciated.