Hi,
As you know and as you mentionned, the CCavenue plugin is developed by the TechJoomla team under their common payment plugin.
So the best is to contact the TechJoomla team for the modifications on the plugin in order to have an up-to-date plugin with the CCavenur API ; it will also help the rest of the community who is using TechJoomla CCavenue plugin.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.