Board recommendation for project with GPRS requirements

Hi guys!

I've a project with raspberry pi B+ and a usb modem for communication with server. Is a unattended system but I've many problems with communication cuts and memory card corrupted. Communications is not important issue, because isn't a real time system, and I manage the cuts with own scripts. In the other hand, the memory card corruption is a damn headache.  I think that problem is caused by the model B+ because I've other similar project with model A+ and I haven't this problem.

The reason for my question is that I'm looking for alternatives to the raspberry pi B+. I tested Orange Pi 2G-IOT, but is very unestable and I discard it.

What borad do you recommend me with this requirements:

 - Compatible with my C code

 - Compatible with GPIO (if is possible) because I need a RS485 port and I've a hat

 - Estable GPRS module (better if is integrated on board)

 - And as always, better if is cheap

Thanks so much for advise!!