AR: Buy GTINs/UPC/EAN barcodes

My products did not have GTINs; they were custom products with Symprosys. It showed me limited stock on Merchant Centre as not approved. I downloaded this application, added GTINs to each product, and my Merchant Centre account still shows limited stock! So this application is useless. The GTIN numbers do not exist on the GS1 website, which is the basis for finding a GTIN, so Google must not recognise them!