Hi @zimma71
I'm sorry to learn of the issues your experiencing with your phone.
May I ask which model of phone your using in the A Series Range ?
May I also ask and offer some tips ....
- Is phone calls dropping out everywhere you go or in a particular area ?
- If you insert your Sim card in another phone do calls hold Ok [ obviously if you have another phone you can try. ]
- Can you try another sim card in your phone and then see what happens ?
- Are you able to check your networks masts via any relevant online network checker they may have.
- Sometimes a sim card can glitch to which a sim swap to replace it can help. Your Network can arrange this or your local Network Highstreet Store.
- Going into Settings, General Management, Reset, Reset Network Settings May help.
- If your network allows Hotspot Data connections then there should be no reason why this wouldn't work. It could be the device your using to connect to share your data allowance.
You can send feedback via your Samsung Members App under the GetHelp section along with any relevant error reports so Samsung can take a look at what your experiencing.
Also sometimes clearing the phone's System Partition cache file can help.
> Clear Cache Files from the phone's System Partition Section > https://www.samsung.com/uk/support/mobile-devices/how-do-i-clear-the-cache-on-my-device/ You may need to insert your earphones or hook upto a powered On Laptop to access the Clear Partition Section. This may help with lag or stutters as this clears the phone of old/unused or broken cache files.There is also a Repair Apps option in the Menu System too.
As a last resort a back up and factory reset may help.
Software updates rarely affect a phone negarively but it can happen sometimes due to a rogue app that's causing conflict or indeed something in the update.
A person can check via > Safe Mode > https://www.samsung.com/uk/support/mobile-devices/how-to-start-my-galaxy-device-in-safe-mode/ turns off downloaded apps and themes etc which may highlight an app or theme that's causing conflict.
I appreciate it's frustrating when one's phone doesn't work as it should.
A Samsung Experience Store or Samsung Service Centre can check out your phone too.
I wish you all the best. 
