Aldi Bauhn AAP5-815 phones not recognising sim card

[AC Question]

I purchased two of these phones a few weeks ago and both of then frequently show "no sim card".
The first time it happened I phoned the support number and they suggested turning off the phone, removing the sim and replacing it and then restarting.
When this didn't work they suggested to do a factory reset.
This did the trick but unfortunately the problem has re occurred three more times.
I am getting tired of having to do factory resets all the time.
Any suggestions on what could cause this to happen and how to fix it please?
Phone details are: CPU is MT6735M, OS is Android 5.1

 

[JJ1st]

I had the same problem with my phone (same model as yours) had to send it back to Tempo for repair