B787 Captain reported the DG documentation erroneously listed a 'wet cell battery' was onboard; with no way of correcting the error. After communicating with multiple parties; the Captain received an ACARS message that stated that no such battery was loaded onboard; and the flight was able to depart.

Narrative

Upon receiving the [DG documentation] it was noted that '*WET CELL WHEELCHAIR* QTY 1' was printed at the bottom. As I had not received the form; I asked [the] First Officer to go down to the Ramp and ask an agent for the form. First Officer was informed that no battery powered wheelchair was boarded. I then spoke with the Gate Agent who confirmed that no passengers with battery powered wheelchairs were boarded. We then notified ZZZ Operations; who said they would contact Load Planning and have the form corrected. After several minutes of no response I called Operations again; and was informed that Load Planning does not have a way to change the form; and that they sent another ACARS message stating; 'NO DANGEROUS GOODS PLANNED.' I told him that was insufficient because battery powered wheelchairs do not use the DG Form. I then called the Ramp Agent on the headset and asked how they document a battery powered wheelchair was boarded. He told me that when one is boarded; a Ramp Agent will scan the tag attached to the wheelchair prior to boarding it. He then told me again that no battery powered wheelchair tags were scanned because they never loaded a battery powered wheelchair.I then called Dispatch and asked if they could assist in providing the corrected form. The Dispatcher said he would contact a Load Planning Supervisor. I then called the Chief Pilot to ask for assistance. The call went unanswered so I left a message with my contact information. After several minutes of no response I called the Chief Pilot again and this time he answered the phone. He said he had not returned my call yet because he was busy trying to correct the problem but he did not know how to do so. He informed me that he could not find anyone in Dispatch; Load Planning; or Operations that knew how to correct the form. He seemed very frustrated and informed me that he didn't think it would happen. He then asked me what I required to depart. I informed him that I needed documentation stating that no Wet Cell Battery Powered Wheelchairs were onboard the aircraft. Soon thereafter I received an ACARS message stating; 'After discussion with Operations and Load Planning; it is confirmed that no wet cell batteries have been loaded in any cargo bin.' I then reported to Dispatch via ACARS that I was in receipt of documentation confirming that no wet cell batteries were loaded and we were good to go. We departed soon thereafter.