Disgruntled account, doesn't generate the revenue to reflect the noise

In brief, we i was just handed over this account from an AM who left and didn't tell me what a minefield that was. Before i realize there was a call from a guy completly angry with our service then I investigated what happened and how we can help only to find the below.

1. We invited him to use portal DLR data same as all our customers does – He Refused
2. Asked him to adjust their application to automatically receive DLR once it is ready. We even offered to walk him or his technical team through this configuration change- He Refused
3. He used to send DLR request in a separate ticket for each number -20 to 40 tickets a day- which ruined our our support teams SLA –
4. So we asked him to collect all numbers in one tickets so we can respond in a timely manner- He Refused.
5. Then, we accepted to receive them in separated – and we collected all the responses in one sheet and sent it back to him – He Refused, under the pretext that he is receiving it that way from his clients and wants to have them separated accordingly so he can reply to each client by just forwarding our reply directly – As if we are acting as a Service Desk for his own company-
6. For the sake of his satisfaction, We accepted to keep sending his requests separated - not as Incident but as Requests – to have a suitable SLA which is 48hrs-
7. Since then, we are dedicating an FTE for 2hrs a day to fulfill his requests in less than 24hrs.
8. Dedicated a SPOC for all his incidents & requests

his Contribution in total is only 1/10th of an avg account to the team as a whole and he is having a bespoke support model same or even more than a fortune 500.

What the hell should I do with this account?