MQTT read response

I am trying to read the bytes from MQTT using SIM800 and STM32.
however I am unable to read.
I have to read a whole message from server after I receive a suback.
I even used Docklight and TMFT to check if I have any MQTT response.
Do you have any idea how do I do that ?
I am using GPRS mbed library for sim800.

You can view data in hex mode. The data that comes to SIM800 from the broker is only 2 bytes in hex format. In text mode they appear as dots in TMFT. There is option to view HEX.