I've posted two previous articles regarding her claims which were mostly based on RT interviews with this Bulgarian journalist (see here and here) who has since been fired. Since then FARS news agency has followed up with this interview (in transcript form) of their own with Gaytandzhieva.
Dilyana Gaytandzhieva is a Bulgarian investigative journalist. In December 2016, she visited liberated neighborhoods of Aleppo where she found Bulgarian-made weapons inside underground warehouses belonging to terrorists. She felt suspicious and traced those weapons to its Bulgarian manufacturer realizing that they were legally exported to Saudi Arabia, which in turn supplied them to terrorists in Syria. As a result of further investigation she discovered that this was just a small part of a bigger international scheme.
FNA has conducted an interview with Dilyana Gaytandzhieva about the result of her investigation into the use of diplomatic flights for supplying weapons to terrorists.