So you are admitting that it is a software issue? Actually communicating that to customers would be a great way to alleviate frustration.
They aren't going to admit to anything that will end up costing them money.
My suggestion is to go to a cell phone modding website (like xda developers) and download the RUU for the particular phone you have. The RUU is essentially a program that will let you roll the phone back to a previous version of the software. (It's a recovery tool for messed up phones.)
WARNING: Running an RUU on your phone can brick you phone, making it a paperweight. Sprint WILL NOT warranty or repair a phone that has been modified. Running the RUU is not considered modifying the phone (as it comes from Sprint), but if you brick the phone, they will not repair it. You're stuck replacing it.
I've been having the same issue with mine. They did uupdates when I called from a different phone now my WiFi calling doesn't work. I also bought the Harmon kardon speaker from Sprint worked great for two months hasn't moved from the table I keep it on and I went to use it yesterday and it won't turn on or charge or do anything. Maybe the Harmon kardon product line isn't worth the extra money
Contact HTC directly. They had my son reset something (sorry I don't remember what exactly). He did that over a week ago and has not had any issues since that we are aware of. HTC is the one who created the update and Sprint just pushed it out... Hope that helps