Wireless keyboard and mouse set KM7120W

I purchased this set KM7120W, which is wireless keyboard and mouse.

https://www.dell.com/en-us/shop/dell-multi-device-wireless-keyboard-and-mouse-combo-km7120w/apd/580-aisy/pc-accessories 

Set arrived to me 2 weeks ago and since i got it i have weird problems.

1. every few moments of writing on keyboard, it fails to send signal from pushed stroke, so for example you type word "greetings" and result is "greeings". Or you want to select 20 files to remove by clicking wih mouse and pushing CTRL and at some point all your selections are gone since it didnt emit signal from CTRL push. i checked with various ways, among many strokes detection software and it just is that you push key but its not being read as pushed

2. every 2 days when i start PC in the morning, set doesnt work at all, not keyboard, not mouse, nothing cant be done at all, the only solution is to eject usb radio transmitter and put it back on, this solves the problem.

I tried updating USB drivers and other drivers related to motherboard (gigabyte aorus k3) but nothing helps, i tried turning off the mobile phone and router and ejecting wifi card to check if there is some interference. Nothing. Also its worth to say that i connect back my old cheap Hama set and it works without any problems as it has been for last 3 years....

I may say that as for price this set is sold for, its embarassing to deliver product like that. What can be done about these problems ?