I have a lot of problems also at ITC in Delhi.
My issues are also not posting at all, to posting the incorrect number of nights!
I have just submitted an email for a 5 night stay which has posted as 4 nights!
I tend to email 4 people at the hotel first off. Then forward to SPG and [email protected]. It is a pain but now keep an email saved with all parties I need to contact after each stay to get the errors fixed

I stay at the ITC in Delhi 15 nights per month, usually under multiple reservations which seems to confuse the staff!
Do you also have problems at checkout? Some days it can take me 30 minutes to check out due to bills being incorrect!