Employment/HR/situation. What would you do?

I work for a fairly large company. And was recently promoted.
Howerever 5 months ago there was an internal position vacant in another department , so I applied for it , interviewed by manager and 2 other people from that department. At the end of the interview manager said that I was hired and to wait for a call with offer from HR department .A week went by-no call- I contacted HR, they said they were still working on my transfer.
In several days I get a phone call from HR saying that someone else was hired for the position. When I asked why ,they offered nothing but saying I did not show enough enthusiasm during the interview. Fine!! So 2 months after that another internal position opens. I appliy get an interview with the manager, manager says she won't interview any one else, she wanted to hire me and for mr to wait for an call with official offer from HR.
Two weeks passed with back and forth communication between me & HR .still no official offer. What would you do next?

usually for internal tranfer even though the new department agrees to take you in - your manager MUST agree for the transfer without which the HR will not do the tranfer.

have you talked to your boss about your willingness to transfer? if no, it may be too late now, as your boss knows that you wanted to move without his permission. and it is upto him to let you go or not. anyway the only way you have is to talk openly with him.

try to convince him though you like his department, you want to try something different and ask him politely to let you go.

though he might want to retain you for whatever value you have for him, most of the managers will let you transfer since there is no point holding someone not interested.

very few could be nasty to you in this kind of situation

good luck

Your own manager needs to be checked with-perhaps they don't want you to transfer-it happens.