Here are Mumbai hotels that list a 24‑hour business centre (hotel name — area). I’ve cited the source for each so you can confirm details or hours directly.

• The Taj Mahal Palace — Colaba. 24‑hour business centre and secretarial/workstation services. (tajhotels.com)
• Trident, Bandra Kurla Complex (Trident BKC) — Bandra Kurla. Property page lists a “24 Hours Business Centre.” (tridenthotels.com)
• Trident, Nariman Point — Nariman Point. Hotel lists an on‑site business centre (third‑party listings indicate 24‑hour availability). (tridenthotels.com)
• JW Marriott Mumbai Sahar — Andheri East / near airport. Multiple property listings show a 24‑hour business centre and meeting/conference facilities. (ph.hotels.com)
• The Oberoi, Mumbai — Nariman Point. The hotel advertises an onsite business centre and press/PR material describes a 24‑hour business centre/team. (oberoihotels.com)
• The St. Regis Mumbai — Lower Parel. Guest services directory states 24‑hour access to the business/library room for guests. (fliphtml5.com)
• ITC Maratha (Luxury Collection) — near the airport/Andheri East. Property listings indicate a 24‑hour business centre. (hotels.com)
• Hilton Mumbai International Airport — near the airport. Major booking sites list a 24‑hour business centre among property amenities. (th.hotels.com)

Note: hotels sometimes change service hours or temporarily modify access; I recommend contacting the hotel directly before booking if 24‑hour access is critical. If you’d like, I can check one or two specific hotels’ official pages or phone numbers and confirm current hours.