Why can't local delivery be made on my online store?

My store is configured to local delivery, and it defaults to shipping for users, and they get the following error message: “This order can’t be shipped to the address you entered. Review your address to ensure that all fields have been entered correctly and try again.”

I had to work this around at the moment by adding a pickup method after a customer complained, waiving the delivery fees for the customer - but I’m sure I’ve lost customers due to that problem - and I WASTED MONEY ON SHOPIFY AND ADVERTISING!

Also the fact Shopify don’t have proper email or phone support also makes me wanna consider alternatives.