GST Payment Verification made to Indian Governement

Hi All - I am an self employed IT Professional. My CA files my GST return on my behalf every month. He files GSTR-3B and GSTR-1. I raise every month invoice to my employed and charge him 18% GST on top of my services. Now my employer is not registered as an Legal Entity in India as they are UK based but they still pay me 18% extra as per turnover requirement for Business in India. I pay this 18% amount to my CA every month minus the Input credit. I logged in GST portal one day and wanted to check how this all works. To my shock I do not see any chalan payment matching the amount which I pay him every month which is 50K+ every month. There are very few chalans and all they have value is like 140, 150 rs max thats all. I also checked my filed GSTR-3B filed return as well and he has put my entire Invoice amount in column b) zero rated tax supplies in GSTR-3B form. In GST-1 he has put the entire amount under Exports Invoice 6A. Also I checked my Credit and Liability Statement for FY 20/21 and seems it is all 0 but matches the ITC claimed part of 37K for entire year. So before I confront him and ask why he has done so and kept the money which was supposed to be paid to Indian Government with him. Is there anything else I need to check or am I missing something. To keep my query simple are Chalans only mode of payment for GST to Indian Government and say for example I need to pay 50K as GST to Indian Government, should I must have that Challan created in GST portal and pay that Challan or there is some other mode of payment as well. All I need is confirmation that CA is paying the amount to Indian Government and not keeping with him, which in my case is highly likely seems so. Please help advise what all I can check from my end further and best way to ask him on this. Attached details, striked data for confidentiality.