I don't think emailing helps. I believe it needs to be knocked off the bill at / just before checkout, just like the "book on Melia.com and get €5/€10/€15/€20 to spend in the hotel" offers. Someone from the hotel has to go through and zero out / discount the relevant spends for the gold breakfast and the online booking food/drink spend.
At really good hotels, at checkout, they say something like "we've taken off your melia website allowance and gold breakfast, can I print you the rest of the bill to review?". Medium hotels they say "hmm, please give me a minute" then manage to correctly remove most.
An email to the hotel likely won't help, as it generally seems to be up to the checkout staff to do the discount/zero... Just allow 10 minutes more for checkout than you would a a US-based US-flagged chain hotel, and bring printed copies of everything (Melia online booking discount etc!)