Great application with bugs, need improvement

Great application with bugs, need improvement. the most important thing is that it stops working and unfortunately you can not operate your store until they answer you, this does not make sense because if it is a Friday they can answer you after 2 days. There must be a solution to run locally on the server. and in addition to renew the products in web version. I get a lot of complains from my client because in a retail store it is not possible to stop working for while because causes chaos.