Hi Imran,
You can try to read the messages that are referenced to a business transaction by reading corresponding BOL entity. Something like this:
DATA lr_core TYPE REF TO cl_crm_bol_core.
DATA lr_entity TYPE REF TO cl_crm_bol_entity.
DATA lr_msg_cont TYPE REF TO IF_GENIL_MESSAGE_CONTAINER.
DATA lt_messages TYPE CRMT_GENIL_MESSAGE_TAB.
lr_core = cl_crm_bol_core=>get_instance( ).
lr_entity = lr_core->get_root_entity( iv_object_name = 'BTOrder' iv_object_guid = iv_guid ).
lr_msg_cont = lr_entity->get_message_container( ).
lr_msg_cont->get_messages( EXPORTING iv_message_type = 'E' IMPORTING et_messages = lt_messages ).
Give it a try! 
Kind regards,
Garcia