Iphone 5s won't allow me to delete any messages and the phone just freezes

I have messages saved on my phone since March. Every time I try to delete a message or message thread, the phone first gets really slow and then freezes. I have try to restart AND reset my phone and all the old messages still appear and nothing has changed. Another problem I have ran in to is not receiving text massages, iMessages, and sometimes not being able to make a phone call. I will simply hit the little phone icon next to a contacts name and the phone will not respond. Please help.