If you really want to get a quality product, then do not look for a separate person - a programmer, but contact the company. After all, if you don’t like something in your application, so that there is somewhere to make a claim. For example, I really like the approach of specialists from this company https://stormotion.io/blog/how-to-develop-a-banking-website/
. Their mobile banking app is really easy to use, convenient and functional. You can then contact them for technical support without any problems!