What should I do if I can't track my son's British passport renewal application through VFS Global?

My son sent off his application for his British passport renewal in March and has had no response to date. He received a digital receipt with a reference number for VFS Global that could be used for tracking his application. After opening up the VFS website and finding the tracking page, many attempts to input the reference number in different formats have led to no success. Anyone else had similar issues and found out how to do it correctly. The reference number looks like this in letters (L) and numbers; LLL/LLL/NNNNNN/NNNN/NN.