Availment of Import Credit (IGST) - Goods and Services Tax - GST

We have manufacturing of Pharmaceutical Machinery Equipment registered under GST Act . We have imported free bottle sample from our customer for machine trial purpose. Customer has shipped bottle sample declaring a value. While clearing the material, our custom authority has charged us Custom duty, IGST on assessable value declared by our customer. Our query is that can we avail IGST credit in above case since we are not paying any material cost to our customer. It is free of cost however we have paid custom duty IGST as Charged by our custom department for clearance of the Goods (Sample).