Hi Jonnywina, as what I'm saying to a previous thread a friend of mine MICH encounter same problem like yours. She's aware of her payment has discrepancy through BDO CASH payment, so on the day of her appointment she was adviced by VFS staff to pay the diffrence at Standard Chartered (I guess that was Florge mentioned the branch located along Ayala Avenue), she able to pay it in the afternoon and same day she submitted her application.
If you could change your flight earlier, why not try a walk in, just in case there will be a problem you have a back up appointment
(like what I did)
, I saw Hotel few step away at VFS if I'm not mistaken it's Tiara Oriental, just google it
and about the Standard Chartered in your local branch try first to phone them if they do accept visa fee discrepancy, it's less hassle if you pay the remaining fee before your flight going Manila, but to my experience there are some conservative banks not aware about the visa fee matter especially if it's located in province local area, if you don't gave them the info's they won't process it and whether wrong or not, we're suffering the risk
Goodluck!