First of all, many thanks for your prompt and informative reply.
And now, sheesh, shaking head. Frankly it's an absolute mess. I have contacted them numerous times, and 50% of the time I got told they do not provide such a document. After a few attempts, I decided to not be as polite, and reiterated to them that they do, and that they have issued this document for others. I asked to speak to someone with more authority and knowledge on this matter, and was put on hold. Upon the telephone agents return, they apologised and said they do provide such a document, and that I was to contact them via some private email. I did, and as of yet, 2 weeks later no reply.
I rang again, and was told there is a backlog hence the lack of reply. I waited a bit, rang again, only to be told they do not provide this document, and topics concerning nationality are handled by nationality enquiries at the Home Office. I email them, no reply. I ring them, they tell me they have no knowledge of such a document. I ring again, and they point me to the online renunciation form.
So I have been given the run-around for about a month, with inconsistent information, and various employees and agents singing from very different pages.
Anyway, upon going through various translations of the required Letter Of No Objection, and the original in Bahasa Indonesia, it appears that it is more a case of I the undersigned hereby declare type of thing, and then they stamp it. Thus, I contact them again, this time to tell them, I can't make an appointment online, as I need to get a letter stamped by them. The reply rather quickly pointing me to where one can book an appointment online. I reply to them, stating I have been trying at that place for a month, but all options are blanked out, nothing is selectable.
However, reading your reply, I am now thinking maybe they still do provide this Letter.
I will be contacting them again tomorrow, and shall ring them. I shall update this thread, and reply to your question when I finally figure out what they do now, cos at the moment, they do nothing other than waste one's time.
Once again, many thanks for your response.