As you are asking for Hindustan Petroleum Gas Complaints toll free numbers so on your demand I am providing same here :

Corporate HQ Customer Care Number

1800-2333-555
022 22863900

Marketing HQ Customer Care Number

022 22637000

HP Gas State-Wise Customer Contact Numbers

The table below indicates the state-wise contact numbers which can be used by HP LPG customers.
State Contact Number
Andhra Pradesh 96660 23456
Assam 90850 23456
Bihar 94707 23456
Delhi (NCR) 99909 23456
Gujrat 98244 23456
Haryana 98129 23456
Himachal Pradesh 98820 23456
Jammu and Kashmir 90860 23456
Jharkhand 89875 23456
Kerala 99610 23456
Karnataka 99640 23456
Maharashtra and Goa 88888 23456
Madhya Pradesh, Chhattisgarh 96690 23456
Odisha 90909 23456
Punjab 98556 23456
Rajasthan 78910 23456
Tamil Nadu 90922 23456
Puducherry 90922 23456
Uttar Pradesh 98896 23456
Uttar Pradesh (W) 81919 23456
West Bengal 90888 23456