How to pass third party payment gateway entries in tally erp

Hello Professionals,.                                                    Could you please resolve the below question ? Basically, We have a website and selling items through website. In this website we are using Third party payment gataway limited(Eg.CC Avenue). If we sell the item in Website, that money goes to Third party(Sundry Debtor). This thrid party member send the money to our Account after 1 week. Eg. Item Cost: 1000/- Goods IGST(5%): 50/- Total: 1050/-(This amount paid by Customer to CC Avenue) But CC Avenue took some amount from the above amount. Per Example they Charged 50/- and 18% Service Tax(IGST 18%). Total They charges 50/-+ 18% of 50/- So 50/- + 9/- Total: 59/- And finally I get 1050 - 59/- = 991/- from CC Avenue to my bank. How to treated above example in Tally ERP 9( With Goods IGST 5% and Service Tax IGST 18%. Please help me if anyone expert inTally ERP 9 GST.                                          Thanks in Advance