The UOB PRVI Payment Facility has been in effect for a few months already, and will only be available until 31 Dec 2017. Essentially, you can purchase miles at 2 cents each. You can essentially earn miles from making miscellaneous payments that would otherwise not earn you any miles through this facility, although you are not required to specify any payee in the process.
Simply fill up this form, and UOB will credit the amount that you have requested into your specified bank account, and charge you a 2% administrative fee on the amount requested. You will also earn 1 mpd on this amount, hence the cost of 2 cents per mile.
The catch is that the amount requested cannot exceed your credit limit across all your UOB card accounts, so timing is key.
I have personally purchased over 100000 miles through this payment facility, and there have been absolutely no issues with the crediting of miles to my account. So, take advantage of this while it lasts!