Sellkite Digital Downloads

I have been using this app for a year and they have CONSTANT issues. Same issue over and over again. People purchase my digital item and then email me asking why they haven't received any email! I have all my emails set to automatically send my digital products. Its been that way since I downloaded this app. When I go look in the app under the orders they show "email not sent" so I click the "send email button" and it says " cannot send". Everytime I contact them they are offline and I usually don't hear from them for 2 days. So brutal. This is an issue that has caused me SO MUCH headache!! I have to manually email the files and respond to all the customers myself. Because this is not the first time they clearly cannot fix it. I am now looking for another app to do the job. The app can't deliver the digital items at random....... not sure what I am paying for. *** Update-24 hours and still no response from them about this ongoing issue.