Phone keeps freezing and stalls

Good day,

I bought 2 iphones (both 5s) one less than a year ago and one 3 months ago. I also bought a MacBook pro. So you can see I really support apple and like the brand.

But the last 3 months my one iPhone 5 s started giving me real problems.

Basically the screen just freeze and stalls. then I cannot use the touch screen. I cannot call nothing!

This has effected me quite a lot as I use my phone to get me into my gate at my house etc.

I went to the Istore in Cape Town (Century City) they said I should delete everything and reset everything. So I did. Still nothing. went to them again and they said they will send it in but that it is probably a glitch or something and they won't be able to fix it!

What!!! and that I can buy a new one at a discount price!! This is crazy. it seems like they got a couple of the same faults on these phones!

I can't afford to buy another phone. What can I do.

Certainly the APPLE brand can fix its own mistakes?

What can I do where can I go?

I can't think that I will buy another apple product ever if this is the type of service a loyal customer gets. I have promoted apple a lot as well this will definitely not happen again!

Please can someone just help me