Organization is reluctant to re-issue relieving certificate with changed dates

My last working day in ABC company was 31-07-2007 and I joined XYZ company on 7-08-2007. I received relieving letter from ABC orgnization dated 13-08-2007 and there is overlapping of 7 days.
I request ABC organization to reissue the relieving letter dated 31-07-2007, however the organization is reluctant to re-issue a certificate with changed dates.
All seniors people, please let me know what is the process to get a relieving certificate with changed dates, since this overlapping is creating joining problem in new EFG organisation which is very much diligent with paper work.

Your official relieving date was 31/7 but you got the letter of relieving dt. 13/8. what is the problem?
Pon

I have resigned on 31/07 and joined XYZ company on 07/08, Now the ABC company informed their head office on 13/08 and they prepared the relieving letter with 13/08.
Now, when i am going to join EFG company , they want new relieving letter with 31/07 and ABC company said we will not change our database.
Just want to know what will be the solution for this problem