Samsung Galaxy S4 Network Switching "Not Registered On Network"

Hello,

I have Samsung Galaxy S4 i9500 and the problem which I am facing is regarding network. The problem is that the network I am using has weak signals inside my house but still there are signals.

Now what my mobile does on weak signals is keep on switching network operators to other carriers and when I try to make a call it says not registered on network although it is showing signals.

I tried to find a solution online which said go to network operators and choose your network manually which did worked but due to low signals sometimes my mobile goes out of coverage and then samsung s4 again changes the settings from manual to automatically and again it switches to another network where Not Registered On Network problem arises.

Do we have any method or app other than manual selection of network operator to lock a operator down or a method which does not allows others networks to be connected because on my LG P-700 when I try to switch networks it says we could not connect that is why there is no issue on that set but my s4 shows signals while it is not registered on any network. Confusing.

So is there a lock or method do let me know.

Thank You